How GMail stores your mail

When folks come to GMail for the first time, they instinctively expect it it to work in exactly the same way as the other email services and email clients they have grown used to.

But when Google created GMail back in 2004, they had an opportunity to re-define email and how it worked from the ground up. So - being Google! - they did.

The result is a pretty sleek and efficient mail management system, with no duplicates, no folders, no separate mail streams - just a single mailbox managed with - being Google! - Search. They also went for threaded conversations as the default, and abandoned the time-honoured spreadsheet-like system of sorting mail by column headings, using Search instead to find mail by sender, by subject or by keyword using a capable and combinable range of search terms.

But whilst this is more efficient and - almost - foolproof in operation, it causes confusion among new users because it isn't the model most of us are familiar with. Here's how Google does it:

Labels not folders

The chief source of confusion is the message storage model.  Google's single mailbox is hard for many to grasp, as they are so used to splitting up their mail into separate folders according to their subject, making copies where necessary, and then freely deleting copies from one folder without disturbing the contents of other folders.
GMail, on the other hand, doesn't put messages in subject folders - it puts subject labels on messages. And that's a whole new ballgame!

The system adds labels like Inbox, Sent, Important - users add their own labels like Work, Vacation, Football, Family, etc. Then to see all messages which have any label, you click the label name in the GMail sidebar. GMail does a fast search in your mailbox, and pulls out all matching mail as a set of search results. And as each message can have many labels, a single message may appear in several sets of label search results. This leads to the assumption that there are duplicate messages in the account - which many people mistakenly delete - but of course there are not.
There is just one single message stored in the mailbox, but viewable by selecting any of its labels. As you can see from the illustration above, when you click on a label, you are only viewing a set of search results - you are not viewing mail which is permanently stored as separate copies in separate locations within the account. Delete a message or conversation from any set of label search results, and you are deleting the only copy from the main mailbox.

Things which go wrong

A particular source of confusion is Sent Mail, particularly when used in conjunction with the default conversation view. Some people like to keep a "clean" Sent folder by moving all the mail they send to another folder and then deleting the copy in Sent. In a traditional client that uses the single-message model, and generates copies to put in folders, your own Sent messages can be deleted without making an impact on anything else. In GMail, when you delete a message you have sent, not only are you deleting the only copy of the message you sent, but the only copy of the entire threaded conversation, including the message you replied to and any other messages within that conversation. The only copy will go straight to Trash.
Sent mail is therefore best considered as just that - a permanent set of search results for mail you have sent. Sent messages can be labelled and viewed using other relevant label searches, but the Sent label can't be removed - after all, a message you sent will always be a message you sent!  

Other people like to reply to a message, put it in a folder, and then delete the original they replied to from their Inbox. In GMail, this will have the identical result to deleting a Sent message. The only copy of the whole conversation will go straight to Trash.
In GMail, to remove a message from the Inbox, you remove the Inbox label - just select or open the message and click the Archive button to do that. Or you can do it manually by opening the message and clicking the "x" next to the Inbox label in the message heading. 

Still others might label a message with both Work and a specific Project label. In a client that would mean two copies - one in each folder. In GMail it means one message with two labels, viewable when you click on either of the labels. When the project is complete, if a client user deletes the copy in the Project folder, the copy in Work remains. In GMail, deleting the message from the Project label search results deletes it from the mailbox, and sends it to Trash, therefore deleting it from the Work label results as well.
In GMail, to remove a message from a set of search results, select the message and remove the appropriate label using the Labels button - or you can do it manually by opening the message and clicking the "x" next to the label name in the message heading.

Using Labels

Using Labels is fast and easy.

• You use the Labels button to assign a label to a selected message or conversation - or you can drag the label from your sidebar into the message.  
• To label a message and move it out of the Inbox in one step, use the Move button - or you can drag your message to the label in the sidebar. 
• To remove a label from a message or conversation, select or open it and use the labels button to uncheck the label you no longer want, or do it manually by opening the message and clicking the "x" next to the label name. 
• Labels can be given colours to distinguish them visually from each other - hover over the label name in the sidebar, and you'll see a little options sub-menu appear on the right, where you can add colours, and choose whether to show the label in your message lists or not, and whether to keep them permanently visible in the sidebar.
• Labels you don't use often can be "hidden" from the labels list - then when you want to use them, click More... at the bottom of the list to find them
• You can also adjust the display of your labels to make the most of your sidebar real estate by "nesting" them - so a number of related topics can be grouped under a parent label, and collapsed and expanded at will.
• If you no longer need one of your user-created labels, you can just delete the label itself - messages that had that label will not be deleted, but will remain in your mailbox, viewable in All Mail, or in search results for any other label you might have given it. 
• Labels are organised with the System labels first, in a set order, followed by your own list in alphabetical order. If you have some of your labels hidden, when you click More... you will see the hidden labels in a similar stacking order. 

Once you know how the system works, and adapt old habits to the new model, GMail is fast and efficient. The database of stored mail is kept to a minimum, with no duplicates and no surplus copies, so your 10Gb of free storage goes a long way. Mail is quick and easy to find, either by using label searches or the main search box to find other characteristics like senders, date ranges or keywords. There are a multitude of other tools to use - some built in and some available as add-ons called "Labs" - and several pages of settings where you can, within limits, customise how GMail works for you.

Some love it. Some hate it. But all in all, GMail's exactly what Google said it was back in 2004 - different!

Wrong email! The GMail "dots issue"

Wrong number!

OK, so you get a call for Jane Anthony - but there's no-one by that name at your house. "What number were you dialling?" you say to your caller. "Oh, 908 5674 5555" says the caller.

"Well," you say "That IS my number, but there's no-one by that name here. You must have a wrong number."

Caller apologises, you both hang-up, and you are both comfortable. Because you both know that wrong numbers HAPPEN. And always have, and always will.

The one thing you do NOT do is immediately call the phone company and demand to know why they gave your phone number to someone else, and how they are going to mend this hole in their security, and you certainly don't ask them if all your calls are now going to this other person.

Wrong street address!

Imagine another scenario....the mailman delivers a letter addressed to your house, using your street number, but it's clearly meant for someone else. This happens all the time, too. Always has and always will. You don't immediately call the US Mail demanding to know why they gave your address to a different person. Nor would you ask them whether this other person was now getting all your mail.

Why? Because we all know, from long experience, that people make mistakes. People give the wrong housenumber to the bank (or the person in the bank writes it down wrong!), other people can never remember their own phone number, and always get two digits the wrong way round - after all, how often do you call your own number? And when you do, doesn't your phone do it for you anyway?

Yet those same rational folks who accept that other people make errors, and will happily accept the results of those errors - unwanted mail, wrong number calls - find it hard to grasp that the identical thing happens with email addresses.

Perhaps it's because email has only been around for 20 years or so, so we haven't yet learned to accept that folks make just as many mistakes with their email addresses as they do with their phone numbers and their house or street numbers. And because we still find the Internet a dark and mysterious place, and have little idea what goes on behind the scenes and how it works, any error is immediately nailed to the on-line equivalent of the phone company or the US Mail. It must be their fault - they must have given someone MY address.

In reality, of course, the mere fact that allocation of email addresses is handled by totally automated systems using totally automated checking methods on totally automated databases means that it is virtually impossible for them to go wrong unless they fall over in a very major way, in which circumstance they would be shut down till fixed!

Let's work through an example....

If your email address is janeanthony@magicemail.com, and another person named Jane Anthony tries to sign up with MagicEmail using that address, MagicEmail will scan their user database, find you, and the other Jane will be told the address is taken, and asked to choose another. So Jane now adds in her middle initial and asks for janezanthony@magicemail.com. "Yep!" says MagicEmail, after another automated search of their database, "we don't have a janezanthony on the list, so you're in!"

Now Jane Z signs into her brand new email account for the first time, and her browser, SnappyDragon, says "I'll remember that for you, then, shall I?" - and bang, her email address and password are stored by SnappyDragon and she never has to type them or even think about them again...

A week or two later our Jane Z decides she'd like an account with FakeBook.com. (© bkc56)  So off she goes to their website to sign up. When she gets to the bit where she is asked to enter her email address, she has to think a bit - "Ah, yes! I remember now, it's my name!" So she enters - yes, you guessed it - janeanthony@magicemail.com. Now, just like Twitless, FakeBook doesn't bother checking or validating the email addresses their users enter before they let them open and use their new accounts. So Jane Z merrily adds a whole bunch of friends and posts a few messages and signs up for notifications of everything....

And guess what. She forgot to add her "z" and all her mail from FakeBook floods into your account!

What do you do? Do you just say "Wrong email!", like you'd say "Wrong number!" or "Wrong street address!"? Well, to be fair, many internet-savvy people do - they just create a rule or a filter, and get rid of this rubbish into their Trash. They know it's just the internet equivalent of a wrong phone number or house number being given out by someone with a hopeless head for figures.

But most of us less-experienced folks just assume that MagicEmail has given "our" email address to someone else as well, and because we are getting that someone's mail, that someone must also be getting all of ours...irrespective of passwords or any other security measures. Fear of the unknown and lack of familiarity with the system makes it hard for us to get a handle on what has happened. We just blame our mail service provider and rarely stop to consider that another user has simply made a mistake and supplied an incorrect email address which just happens to be the same as our own.

So what does this all boil down to?

If you have a GMail or Googlemail account, and you start to receive mail intended for someone who appears to have the same address as you - or a dot-variant of your address - or the same address but at Googlemail instead of GMail - then it is almost certainly just a "Wrong number" style mistake by the other user. And you can be rock-solid sure that if you own first.last@gmail.com there is no other user out there who owns firstlast@gmail.com or first1ast@gmail.com or FirstLast@googlemail.com or any other variant of your own unique username.

Because GMail has made sure that your address is unique - see below for the nitty gritty of how that is done. So next time you receive an email addressed to you that was not intended for you, you can confidently say "Wrong number!"

There's one additional error made by others which can also lead to you getting someone else's mail. GMail put a stop to this more than two years ago, by making you get permission from the owner before you can forward your mail to any other address, but not all email services do this. And many users of other services like to forward their mail to their GMail account and handle it there. If they make a mistake when entering their own GMail address into the forwarding set-up in their other account, and enter yours instead, you could end up receiving mail that is inexplicably addressed to a complete stranger with a completely different username at a completely different domain!

For example, if yet another Jane Anthony has an old account at her ISP with the username dreamteen@herISP.com but likes to handle it through her more grown-up account with GMail, she'd enter her GMail address into the forwarding set-up in the other account. If she forgets that she's actually janeanthony99@gmail.com and just enters her name, that's another batch of "wrong email!" messages you will receive, all addressed to dreamteen@herISP.com. Mystifying? You bet!

You can trace this kind of error by viewing the message headers - open the message and choose Show Original from the dropdown menu next to the Reply button. Any forwarding will be clearly spelled out for you.

So what can you do about it?

Sadly, very little. Unless you want Gmail to read all your mail and decide whether or not it was intended for you, there's nothing at all that GMail can do. They do machine-scan your mail for spammy content and filter that out for you, but they can't use a machine to determine that a message can't be meant for you because:

• you don't have a Twitless account
• your boss is not John Doe Jnr, or 
• you don't have a bank manager called Mr Parsons.... 
• your wife's name isn't Freda

 If it's addressed to you, then they are duty-bound to deliver it - just like the US Mail. Your best course of action is to send a polite note to the sender informing them they have the wrong address for their contact/client/friend. If you find a phone number or an alternative email addy in any of the messages sent to you by mistake, you could even contact the person involved. If all else fails, and if the other user's mail is addressed to a dot-variant of your address or another address entirely, then you can use a filter to send those messages straight to Trash.

Some nitty gritty....

Username polices of the free email services

The main free email services have complicated this whole issue, to be fair. The main problem is that the major well-used services have different username policies.

The basic RFC 5322 specification for the local part (the part before the @ sign = username) of email addresses is as follows:

• Uppercase and lowercase English letters (a–z, A–Z) (ASCII: 65–90, 97–122)
• Digits 0 to 9 (ASCII: 48–57)
• Characters !#$%&'*+-/=?^_`{|}~ (ASCII: 33, 35–39, 42, 43, 45, 47, 61, 63, 94–96, 123–126)
• Character . (dot, period, full stop) (ASCII: 46) provided that it is not the first or last character, and provided also that it does not appear two or more times consecutively (e.g. John..Doe@example.com is not allowed.).

GMail's username policy is the most stringent. To protect users against any possibility of confusion, and to help avoid wilful impersonation, it does not allow most of the RFC-permitted local part characters. GMail flatly refuses any username that is not at least 6 characters long and is a unique combination of letters and digits. No periods are counted as username characters (though they can be used as name or initial separators if the user wants to add them), and capitalisation is ignored. So Jane.Z.Anthony is - to GMail's eyes - exactly the same address as janezanthony. Further exclusions include punctuation, all special characters (except the "+" sign in some circumstances) and any "lookalikes". For example, if janezanthony already exists, janezanth0ny is not permitted. GMail just doesn't allow any obvious possibility of confusion between usernames. No dots, no capitalisation differences, no underscores, no hyphens, no analog "lookalike" characters - only a different arrangement of simple alpha-numeric characters can result in a different GMail username.

Hotmail on the other hand - I was surprised to discover - DOES allow periods to differentiate between otherwise completely identical addresses, and was prepared to let me sign up for an account which was identical to an existing account except for a period in the middle. I found exactly the same at Yahoo. The pre-existing address was refused - the moment I added a period it was accepted. Yahoo was also willing to let me add a zero in place of an "o" and generate yet another new username.

It's no wonder, then, that so many GMail users find it hard to accept that Jane.Anthony and janeanthony are - as far as GMail is concerned - the same user. But it is not possible, unlike with Hotmail and Yahoo, for those two usernames to co-exist separately within the GMail system - the system will not and cannot allow it.

So which username policy is preferable?

As a GMail user I am naturally biased. But the whole push of the GMail system is towards increased user security and increased difficulty for those who wish to compromise GMail users.

Any possibility of making life harder for the bad guys by preventing confusion, impersonation and identity theft has got to be a good idea. Sadly for the other service providers, they now have so many users with what GMail would call 100% duplicate addresses that there isn't much they could do about increasing user security even if they wanted to. When janeanthony and jane.anthony and jane.anth0ny and janeanth0ny are all considered to be "different" email usernames, by both Hotmail and Yahoo, that horse has well and truly bolted and there's no point in belatedly shutting the stable door...

But there has just been a great opportunity to straighten up and fly right for Microsoft - except that they chose not to. Their new Outlook service - which was a firstclass opportunity to start again from scratch with a more secure and protective address policy for users - allows easy-to-hack 4-letter usernames, for a start. It also allowed me to sign up with myfirstmylast@outlook.com as well as myfirst.mylast@outlook.com - so the confusion will continue to reign, users will continue to have their security compromised by a lax username policy, and any ill-wisher can appear to have replicated a user's email address just by adding a dot or using "lookalike" characters.

In the meantime, Gmail users - whilst they will find the GMail policy on usernames hard to grasp because it runs counter to everything they are used to - are protected by Google as far as is possible from any wilful and deliberate replication, and all the accidental stuff as well.

References:

Someone Else's Mail - http://support.google.com/mail/bin/answer.py?hl=en&answer=10313
How to use Filters - http://support.google.com/mail/bin/answer.py?hl=en&answer=6579
Show Original - http://support.google.com/mail/bin/answer.py?hl=en&answer=22454

Beyond GMail's Themes

New in GMail Themes is a huge range of images you can add as a background to Gmail. Or you can choose your own image if you prefer.

Google currently provides a choice of a light or dark overlay, just like those in their pre-built themes, but there is no way to modify them and no way to change the text colors

So here's how to do that yourself!

There's a very simple script below for Stylish in Firefox or Chrome. Stylish is a browser extension/add on which lets you easily install and manage userstyles - "themes" for web sites created by modifying a site's Cascading Style Sheet (CSS). You can add, delete, enable, disable, and organise your userstyles with a few clicks of a mouse. Stylish's companion website, userstyles.org, hosts tens of thousands of user styles made by other Stylish users that you can try.

This short script for Stylish lets you change:

1. Unread message background colours and degree of opacity
2. Unread message text colours for sender, subject and timestamp
3. Read message background colours and degree of opacity
4. Read message text colours for sender, subject and timestamp
5. Background colour and degree of opacity for messages you have selected
6. The colour and opacity of the line which divides your message rows in the list
7. The colours of alternating message in Conversation view, to help you distinguish one from the other

First of all, install the right version of the Stylish browser extension from userstyles.org, depending on which browser you are using, Firefox or Chrome.

Pick your image next - you can upload one of your own from disk, grab one you uploaded earlier from My Photos or Picasa WebAlbums or choose from the gallery provided in the new Custom Background theme. Work out what colours you think will go well with it.

Then go here, and look up those colours and their RGB codes.
http://www.rapidtables.com/web/color/RGB_Color.htm

There's a long list of toning colours, grouped in "families", giving all their RGB numbers, or you can pick your own from the colour pickers at the top of the page (see left).

Choose your colours, write down the RGB numbers you want to use for (1) to (7) above and then just alter the script to suit you. You can do this by pasting it from this page into any text editor like Notepad or TextEdit - but be careful to only change the RGBA/RGB numbers.

Here's the script...

It's currently set up with my favourite green background/text colours which work well with GMail's standard Turf and Teahouse themes, and will work with any image that has green as the main colour. You can use it exactly as it is if you like green!

If you'd rather have other colours, all you need to do now is to plug in the new RGB values for the various elements that you have previously chosen and written down.  Copy the following lines of code into any text editor.

/* Unread rows - background colour and opacity and text */
.zE {background-color: rgba(230,255,210,0.95) !important; color: rgb(0,80,0) !important;}

/* Read rows - background colour and opacity and text */
.yO {background-color: rgba(210,240,190,0.8) !important; color: rgb(0,80,0) !important;}

/* Selected rows - background colour and opacity*/
.x7 {background-color: rgba(255,250,205,1) !important;}

/* Row dividing line colour and opacity */
.xY {border-color: rgba(140,190,140,0.9) !important;}

/* Alternating message colours in Conversation View */
div.h7:nth-of-type(odd) div.adn.ads, div.kv:nth-of-type(odd){ background-color: rgba(190,220,180,0.65); }
div.h7:nth-of-type(even) div.adn.ads, div.kv:nth-of-type(even){ background-color: rgba(230,255,210,0.85); }

How to amend the script for your chosen colours

To break this down and make it simple, let's take the first line above:
.zE {background-color: rgba(230,255,210,0.95) !important; color: rgb(0,80,0) !important;}

.zE is the Unread message row. To set the background, you need to alter the first three RED numbers in brackets after the "rgba" - that sets the colour. Then alter the fourth BLUE number inside the brackets to control the opacity of the colour you have just set. The scale is 0.05 to 1.0 in increments of 0.05 - and you can set any level that you want to change the look of your style.

As an example, here's a similar screenshot to the green one above, which is set to have opacities of 0.85 and 0.9 - with opacities set at 0.5 - quite a difference!

Then move to the color element further along the line which is just "rgb" - that controls the colour of the text for the sender, the subject and the timestamp. You don't want these to be transparent, so there is no opacity control - just alter the three numbers within the brackets to use the RGB colour you have chosen.

All the other lines in the script work exactly the same way. Change the RGB numbers and select the opacity level if it is shown.

Here's how Conversation View looks - even with the recent improvements, this colour alternation makes it easier to tell one message from the next, and the slightly darker coloration of read messages makes it easier to see what you have read and what you have not read:

And finally....install your script and view it in GMail!

When you have it all tweaked, save your text file, but keep it open, because you'll want to copy from it.


In your browser go to your GMail tab and click the Stylish extension icon - Chrome top right, Firefox bottom left. The interfaces are slightly different in Chrome and Firefox, but it's easy to find your way around.

In Chrome, choose "Manage Installed Styles" and then click the "Write new style" button. A new tab will open (see below) for you to create your code. Copy and paste in your style, give it a name and save it.

You should also add the URL of the site you want it to apply to - in our case, mail.google.com - so from the URL drop-down choose "URLs on the domain" and type "mail.google.com" into the box.  Save the style again. Then go back to GMail, and from your Stylish menu, choose the name you gave your new style and click Enable to apply it to GMail.

In Firefox, choose Write New Style from the Stylish menu to get to the code window, and follow the same procedure. To apply your style, click the Stylish icon and check the style you want to use.

If you want to tweak your colours further, or alter the opacity of the various elements now you can see them on the page, click the Stylish icon in Chrome, click your style and choose Edit.

Or in Firefox, click Manage Styles, and choose the Edit button alongside your style name. You can do this any time.

Last of all, here it is pre-built for you, as an easy installable userstyle right from the userstyles.org site with an easy method of choosing your colours - just click the link and get choosing....

GMail Message List Colours

See http://gmail-miscellany.blogspot.co.uk/2012/04/userstyles-for-gmail.html for a bit more information and some more screenshots

Making more scripts for different colour schemes

You may be the kind of person that likes a change. So you might want several styles, set up to use different colour sets to go with your favourite background images. To do that, click the Stylish icon, find your script in the Stylish menu and click edit. Select and copy the script in the box. Close the edit window. Then click the Stylish icon again and choose Manage Styles and Write New Style (just as you did before) and paste in the code you just copied. Change the RGBA/RGB values to the new colours of your choice. Give your new style a name and save it. Then head back to GMail to see it working. To switch between your colour styles, use the Disable/Enable options in the Stylish menu.

If you have more than one account, and like to have them open at the same time using Multiple Sign-in. the same userstyle will be applied to both accounts. To differentiate them, you can choose different backgrounds - either a standard GMail theme or an image from the gallery in the new Custom Background theme, or one of your own - that tone nicely with the colours used for your message list.

Here are some more screen shots of what you can do using just these few lines of code. I've used my Spam label so that I need to do the least possible redaction to keep the images clear.

If, having digested the above, you really don't want to start messing with GMail's style sheet, there are a large number of pre-written GMail userstyles available at userstyles.org, as well as the one I have written for you (see above) based on this script. I wrote about those in an earlier blog at http://gmail-miscellany.blogspot.co.uk/2012/04/userstyles-for-gmail.html - and you can just install them into Stylish and use "as is".

A particularly useful one - which also mimics the "old inbox look" to a large degree - is "Marina Resurrected". Find it here: http://userstyles.org/styles/65048/marina-resurrected

Unlike many of the pre-written styles, this one allows you to pick your own colours and customise the script before it is installed into Stylish.  Each element is listed, with a colour picker beside it, and you can choose from the Marina background or a solid colour - or if you are using the Custom Background theme or another GMail theme, then it will work with any of those images too. The style can also remove the People Widget and the ads in an open message, freeing up that space for wider messages.  Here's how it looks with one of the gallery images, and a small tweak to the colour of read messages:

Acknowledgement

I must thank all those busy coders at userstyles.org who publish their userstyles for other GMail users to share. I was able to browse their code to find the most straightforward and robust way of making a short colour-changing script, and could not have written this simple little style without their generosity to other GMail users. In particular, thanks are due to bookdragoness for Marina Resurrected, and C26000 for the Real GMail Turf Theme, both of which helped me write the original script, and produce the pre-built version now available at www.userstyles.org.

Customise GMail with Userstyles

There is a huge collection of GMail userstyles published at www.userstyles.org, and more are being added all the time.

Using these styles is easy for users of Firefox and Chrome. You simply install the Stylish browser extension, available on the Userstyles website. Then, when you find a style you like, you will see an install button on the page to install the correct version of the script for your browser. The styles install directly into Stylish and don't litter up your extensions/add-ons list - that means if you don't find anything you like, you can just remove or disable Stylish from your browser extensions/add-ons list and everything will be gone.

Userstyles can even be added to Internet Explorer if you don't mind delving into IE's settings. You need to apply the scripts across to the board to all websites, but as the GMail CSS is very site specific, doing that is unlikely to make alarming changes to any other site but the GMail web interface.

Here's how to do it. First choose your GMail style at www.userstyles.org. Use the Show Code button to see the script itself. Copy and paste the code into Notepad or a similar text editor and save the file to your computer with the .css extension.  Then go here and follow the steps set out: http://webdesign.about.com/od/css/ht/htcssuseriewin.htm

For Stylish users, userstyles can be easily and quickly turned on and off, deleted or edited by clicking the Stylish icon in your browser  toolbar and calling up the Stylish menu - you can also check for updates using this menu. In Chrome it will appear in the top right, and in Firefox it lives in the bottom left.

All the styles are written by GMail users for themselves, and published for others to share. A keen user will keep his style updated as GMail changes, and the best style developers update their styles regularly at www.userstyles.org. However, they are not endorsed by Google, and could break at any time if the GMail code changes.

Some of those that work well with the new interface of GMail include:

GMail Theme
For those who like blue, this style loads a custom blue background image (stored in a Picasa Web Album and linked to the style with the image URL) and adds a blue background or read messages, with an ochre colour - similar to the old GMail orange - for the unread messages. Hover colours are slightly darker. The style also adds a border to the work area, similar to the old interface.
In a Compose or Reply message window, the message frame is now pale blue instead of grey.
In Conversation View, the subject is highlighted with blue

One interesting point about this style for users who like to customise their look is the background image. This is simply a photo stored in Picasa Web albums - replacing the URL in the script with the URL of one of your own Picasa Web Album stored images will add your own chosen picture instead of the blue background image.

This needs to be used with the Dusk theme in GMail's theme gallery, to make sure of getting the right text colours
NB This does not work with the Right Side Chat lab, nor with a vertical split selected in the Preview Pane lab.

Gmail - Highlight Unread Mail (Blue)
This is very simple indeed, and does exactly what it says on the tin and no more - but it does make an amazing difference to the look of even the default light theme.
The style is so simple that it is easy to edit to use any highlight colour of your choice, once you know the hex code for it. You can look up Hex codes here: http://www.rapidtables.com/web/color/RGB_Color.htm or at http://www.colorpicker.com/

GMail New Preview Theme
This userstyle is even simpler - just two lines of code to change the colour of the text of unread mail. It comes with red set as standard, but is easily edited to the colour of your choice by replacing the hex colour code. Here it is in dark blue, as an example:

GMail Real Turf Theme
This simple style for use with the Turf HD GMail theme amends the read/unread message list colours to green and darker green, very similar to the way the Turf and Treetops themes looked in the old interface. It fills a big hole in the current theme gallery, as there is nothing there which is comfortably usable by people who like green!
In Conversation view, every second message is also highlighted in a pale green/blue shade, to distinguish messages from each other more easily.
This style is quite simple and could easily be edited to match with other non-green HD themes by changing the colours.

New Gmail - Read / unread contrast increase
This style does nothing other than increase the depth of the grey highlight for read messages. Before installing it, you can choose how much contrast you want. It has only three lines of code, each containing a colour specification and transparency specification, so is very easy to edit yourself by changing the colours and the transparency - you could have a pink or purple background for your read mail, for example!

Gmail - Show Gmail/Contacts/Tasks menu items
Those that are irritated by the two-click access to Contacts can install this style, which - after the first use of the main menu - keeps the main menu expanded horizontally into three clickable links to Mail, Contacts and Tasks.

Gmail messages, rounded and compressed
The recent update to conversation view has made a significant difference to its readability. But for those who still want the borders and rounded corners of the old interface, this style works effectively. Messages in a conversation are now more easily distiguishable from each other, and from the right-hand column.

New Gmail without any of the annoyances
Whether you like this style will depend on what you consider to be annoyances and what you consider to be important. It renders the Compose button almost invisible, for example! It makes the black top bar semi-transparent, which only really shows in a light theme. It functions with many of the dark themes effectively, but - as noted by the author - some tweaking of text colours may be required for it to work with all themes. In Conversation View, the entire message area has a dark grey background, which seems illogical - but can easily be changed once you identify it in the script.
The only way to discover if you will like this is to try it!

GMail Easy Access Coloured Buttons
For those that like the icons and haven't switched back to text, this style colours the icons on the buttons. It adds a spot of colour to the page as well making it easier to distinguish between the icons - Trash, for example, is bright red! You get a choice when installing to install for a light or a dark theme - the dark theme selection gives brighter colours.

Gmail menu and auto-completion highlighting
Many GMail users have commented that the standard colour used to highlight your selections in various dropdown menus is too pale to be easily visible. This simple style fixes that - the default colour is blue, but as the author - GMail user David Kewley - points out, the colour can be easily edited after installation to be any colour you like.

And finally...here's one I made earlier:


GMail Message List Colours
This style lets you choose your own colours for read/unread and selected mail in the Inbox and other lists, and applies colours of your choice to alternating messages in conversation view, to aid in distinguishing one message from the next. You make these choices from the Style page before installing the userstyle.  Here is the result of using the default settings, with a custom background of my own uploaded into Gmail's new background theme, which is rolling out right now....

I have drawn upon the skills of several other userstyle authors to produce this style - notably "bookdragoness" for leading me to the trick of allowing users to pre-select their own colours, and to "C2600" for help with defining the correct elements for altering the colours in message lists.

You can also use the style with any of the GMail themes - here it is with TeaHouse and the default colour set of various shades of green.

Other Userstyles
There are a host of other styles available at userstyles.org.  Several of them attempt to recreate the "old look", and these are prone to breaking because they are very complex. Return to Old GMail, GMail b2b and the GMail 2012 Merge style have all lost their lefthand sidebar scrolling ability, and Return to Old GMail has no scroll bar at all in the central pane. However, it must be noted that these styles are among the most complex, and are more liable to break than the simpler styles which refer to only a handful of elements. All of them have already required several updates to keep pace with the subtle changes which occur in GMail on an almost weekly basis. Safer is simpler - and most of the styles outlined in this article are just about as simple as it gets!

GMail's own options
The above are just a small selection of userstyles I have tested with GMail, and for which there appears to be user demand. However, it's worth remembering that GMail's own built-in options can also be used to restore text to your buttons, choose to have less space in your listings, transform the look and feel and banish the glaring whiteness. The following images are of the Ocean theme at varying times of day, with text on the buttons and compact density selected. I've also collapsed Chat leaving the sidebar free for my labels:

Google Accounts - how they work

One common theme running through all the Help Forums is confusion about Google accounts and what you can and can’t do with - and to - them.

So what exactly IS a Google account?
A Google account is an entity that is permanently linked to a unique and specific ID - always an email address (and not necessarily a GMail address - see below) - which you access by signing in with that unique ID and a password. It can house one or many Google products, such as GMail, YouTube, Docs, Calendar, Blogger, Picasa....

In fact, a Google account is rather like a house. It has a unique street address - its username. The house has several rooms in which different Google products are located. Each product room has its own filing cabinet where the product data is stored. The Google account ID is the key to the front door of the house. Once you put the key in the lock and turn it - i.e. sign in to that account - you can access all the products and all the stored data in the filing cabinets in the various rooms. In the lobby of the house on the telephone table is the address book for that account - the Contacts List. Most of the products in the house can use the Contacts List and some can update and add to it.

How do I get a Google account?
For many of us, the creation of a Google account happens automatically when we decide to start using GMail, and create a Gmail account. The username you choose when creating the account becomes your permanent GMail address for that email account, and is also used as the unique ID for the Google account which houses your email product.

If you don’t use GMail, until recently you could still create a Google account - to use, say, Docs or the Calendar - and link it to an external email address that you have at Hotmail or Yahoo or your ISP’s mail service.  If you later add the Gmail product to such an account, then the username you choose for  the new Gmail account automatically becomes the “primary” ID for that Google account. But the original ID remains permanently connected as a secondary ID, and you can use either the Gmail address or the original ID to sign in. The “primary” ID – the Gmail address – is the one that will be used for display purposes in the top right corner of your Google account pages.

These non-Gmail secondary addresses are called alternate addresses or alternate IDs - you can sign in with them as well as with the Gmail address, and they are a real alternative ID for the whole account and all its data. 

You can add an alternate address/ID to a Gmail account if you wish. Any non-Gmail address that is not attached to or linked with another Google account can be added. Google will verify it, and that you own it, before they will allow you to do  it, but after that, you can use it interchangeably with the Gmail address as the account ID.

This can in fact cause some baffling problems as it is easy for inappropriate addresses to be added as alternates.  Many people, for example, confuse alternate addresses with simple recovery email addresses, and inadvertently set up alternate IDs instead of just adding a recovery email address.  This happens most between husbands and wives, close friends, partners - one party will add the other's non-Gmail address as an alternate ID instead of a recovery email address.  The opposite party willingly verifies the address, and so that address now becomes an alternative ID for the original account.  

That's how husbands end up with their wives' names and pictures on their Google Profiles and even on their outgoing mail!  It's why a woman's business colleagues will see entirely the wrong contact information when they receive an email from her.  It's how Facebook look-ups done by Outlook.com/Hotmail users go wrong and get linked to incorrect information. 

But it's easy to put right - just sign into the original account and in Account Settings, remove the alternate address, before re-adding the same address as a simple recovery email address instead. A recovery email address has no ID implications, and the account will revert to its original single Gmail ID. 

For more information on this last topic of mismatched-profiles caused by inappropriate alternate IDs, see http://gmail-miscellany.blogspot.co.uk/2013/04/wrong-picture-wrong-name.html

How do I use my Google account?
Once you have a Google account, you can add any Google product of your choice to that account. The ID of the Google account becomes your ID when you use that product. Any data you create using that product is stored under that ID. When you sign in to that account, you can easily switch between the products you have added to that account by choosing them from the top Google Bar.

Many people do not appreciate this structure, and simply sign in to GMail to check their mail, and sign out again when finished. Consequently, when deciding to try out Picasa or Docs, they are asked to sign in or create a Google account. As they don’t realise they already have a Google account which houses their GMail account, instead of signing in with their GMail ID, they create a new Google account. When they decide they’d like to start a blog, they go to Blogger, and repeat the same process. So many users actually end up with multiple Google accounts, each one often used for only one or two products, and have to sign in and out whenever they switch products so that they can access their stored product data.

Right data - wrong account?
That’s how we can end up with product data being linked to the “wrong” Google account.  Let’s try some examples to see how that can happen:

• Fred is signed into the Google account he uses for Picasa, for example, when he decides to draft an article for his next Blog post - he clicks on Docs in the Google bar and is taken to the Docs product. He creates a new Google document, starts writing his article, and saves it. Next day, he signs into the Google account he uses for GMail, checks his mail, and then decides to finish his article. So he goes to Docs from his Google bar, and finds to his horror that his document is missing!  It isn’t, of course, but he is signed in to a different Google account to the one in which he created his masterpiece the day before so that document isn’t available to him.
• Or John sets up Google+ whilst still signed into the Google account he uses for work. He spends time setting up Circles, adding his contacts, and browsing his Stream.  Next day, he checks his personal GMail account for email, and whilst there decides to check for new things on Google+. To his shock, when he clicks on Google+,  he has no Circles, no Stream - it’s all gone!  Not at all - it’s still all there in the Google account he used to create it, but it is not accessible unless he is signed in to that account. And what’s worse, he realises he doesn’t want Google+ linked to his professional account - he really meant to add it to his personal account.
• Even worse is when a relative comes to visit and signs in on your computer to check their GMail for new messages. They forget to sign out - and you decide to do something you’ve been meaning to do for weeks, i.e. create a work Calendar. You go to iGoogle, and without checking the sign-in info in top right hand corner, click on Calendar and labour away putting all your work appointments and reminders into a new Calendar. But sadly, your nice new Calendar is now firmly connected to your mother-in-law’s Google ID....and is only accessible to you if you are signed in with her username and password.

The solution wanted by most people who make these inadvertent errors is to simply merge these accounts and bring all the data together under one Google account ID, or just swap whole products in and out of various different Google accounts. But merging isn't possible, and swapping product data between accounts isn’t available for all products.  See the links below for what you can move and what you can't. 

So why isn’t it generally possible?
Let’s go back to our Google account house...

A few doors down from our “house” is another Google account. It has the same layout, with various Google products and their data occupying the different rooms. It may have a few different products to the house up the street - it may, for example, use You Tube and maybe it doesn’t have a GMail account at all. It too will have its own address book on its own telephone table in its own lobby. But to enter this house, you can’t use the key from the house a few doors up. You have to use a different key - the unique username or “street address” for that house - before you can open the front door.  And when you DO open the front door, and start visiting the rooms where the products live, you will find completely different sets of data in the filing cabinets. Even the address book on the lobby table is different to the one in the house next door....

Now imagine you owned both houses, and you wanted the products in the first house to be able to open the filing cabinets in the second house and vice versa. But they don’t have the front door key, so they can’t get in through the front door. You cant change the locks so that the same key opens both doors - you’d just screw up the data, because none of the products would know which filing cabinet it ought to be storing its data in, and none of the products would know where they had to look for their data.

The only way you - as the owner of both houses - could do it would be to unlock the door of the second house, photocopy all the data in the filing cabinets in the second house, and laboriously cart it up the road to the first house, unlock the door, and file away the copy documents in the correct filing cabinets in the first house. And what if the first house doesn’t use YouTube when the second house does? You’d have to build a new YouTube room and get some new empty filing cabinets to put the data in. Tedious? You bet!

This house-moving is what the Data Liberation Front - a team of Google engineers - is trying to help us to do more easily. (http://www.dataliberation.org/) Many of the documents in the filing cabinets in the various product rooms - and the address book in the lobby - CAN be copied, and the copies just walked up the road to the other house and filed away. Others can’t, and right now there’s no way to get some data out of one Google account and into another. You just have to delete the product entirely from one, and recreate it from scratch in the other.

There can be an alternative to physically moving data - with a few products, like Docs and Calendar, you can share their data between accounts. Shared data remains separately stored in the account it belongs to, but can be displayed (and some cases edited) in the other account. This is rather like giving the Calendar room in the first house a remote access connection to the Calendar room in the second house! It still involves both accounts being maintained and active, but can minimise the need to sign in to both.

Avoiding this scenario:

• Know what you are doing with your different Google accounts and understand that they are different from each other. When you want to start using a new Google product, don’t create a new Google account just because you don’t happen to be signed in at the time - decide which Google account you want to add a new product to, and sign in to that account. Then add the product.
• In particular, don’t sign up to Google+ unless you are sure you are signed in to the account you want to use with Google+. You can always check this by looking up in the right-hand corner of your page, where your email address is displayed. Right now getting 100% of your data out of one Google+ account and into another is not possible. You can use Google Takeout to transfer your Circle connections to a second account, provided that the second account has been created using the same Profile name as the first account.  But your stream, and some other data, whilst it can be exported, can't be transferred. 
• Understand the “Keep me signed in” checkbox and what it does - it sets a cookie to keep you signed in to that account for 14 days. If you have this checked, and do not sign out of your Google account when you shut down for the day, when you start up your browser next time you will be signed back into that account automatically, and will bypass the sign-in page altogether. To use another one of your accounts, you must first sign out of the account you are currently signed into, to get a sign-in page where you can sign into the the other account.
  This is important for those who have just created a new account. Many users think GMail has deleted their old account when they set up a new one, because they select “Keep me signed in” the first time they access the new account - so they always bypass the sign-in page, and are never offered the chance to sign back in to the old account.
  And it is particularly important for users of a shared computer - if individual users do not sign out at the end of their session, but just close their tabs, another user trying to access their own account will be taken straight to the account that is still signed in, with no opportunity to sign in themselves. This has poor security implications as well as being frustrating.
• Investigate Multiple Sign in, which allows multiple accounts to be signed in during a work session. The first account signed into during that session becomes the “default” account for that session. Subsequent sign-ins to other accounts become subordinate to the default for the duration of that session. Signing out of ANY of the accounts terminates the entire session and all accounts are signed out.
  This is helpful for many users - I find it invaluable to have my personal and work accounts both signed in, giving me access to the two separate GMail accounts and the different data collections associated with the products I use in each account. To get to my personal Docs, for instance, I just swap to the personal account tab and click Docs. If I want to review some images I stored in Picasa for work use, I switch to the work account tab, and click Photos. In our house analogy, this is like unlocking both front doors and trotting back and forth between the two houses.
  Some Google products don’t yet work with Multiple Sign in, so if you wish to access, for example, YouTube, at any time during the session, then you must make sure that the account you use for YouTube is the default account for the session, by signing in to it before you sign in to the other accounts you want to use simultaneously.

And finally...

• Managing multiple Google accounts needs some discipline and does require planning if you are to get the best out of your working environment. So, to summarise:
• Remember that if you use GMail you already have a Google account, and there is no need to create additional Google accounts for other products unless you specifically want to keep them separate from your email IDs.
• When signing up for a new product, think about whether that product can go in one of your existing Google accounts, or whether it needs an account of its own. Act accordingly by signing in to the relevant account, or creating a new one.
• When signing up for a new product, make sure you are NOT already signed in to an account you will regret associating that product with! Always check your address in the top right corner of the page.
• Don’t use “Keep me signed in” as a matter of course on all your accounts and always sign out from any account you are finished with UNLESS you are using Multiple Sign-in and still want to keep other accounts for the session open.
• Simplify working with several accounts at once by using Multiple Sign-in where it is helpful, but make sure you know the rules!
• When deleting an account, make sure you confirm first (1) which account you are actually deleting (check the top right corner again!) and (2) which products you have attached to that account. Understand that you are deleting all that product data as well. If you want to keep any product data, export it (where possible) first.
• If you make mistakes, ensure you know what you can and can’t do with your data by using the advice in the Help Centre and on the Data Liberation Front website.
• To help cope with utter disaster, make sure you do backup your data regularly. Check what export procedures are available for all your products: Docs can be downloaded to your computer, while uploaded Picasa images and YouTube videos are probably still there. Contacts can be exported, as can your Calendars. GMail can be backed up in a range of ways. See http://gmail-tips.blogspot.com/2012/01/gmail-backup.html for detailed info on how to do that.

Google Accounts Help: http://support.google.com/accounts/?hl=en
Create a Google Account:  https://accounts.google.com/signup
Adding GMail: http://goo.gl/KlOHE
Adding other products: http://goo.gl/MZ1tk
Managing your Google Account: http://goo.gl/Mfhh6
What you can move and what you can’t: http://goo.gl/zDT9R
Moving Google+ Connections: https://www.google.com/takeout/?pli=1#
All about Multiple Sign-In: http://goo.gl/7F2tf
About Keep me signed in: http://goo.gl/v9lvh