No support for tags. While some MUA and webmails now migrated from folders to tags or labels, IMAP still uses folders, so for instance in Gmail I have "Projects" and "To do" tags, if a message has both labels, in IMAP it is physically duplicated. Sorry for the confusion.
When you've enabled IMAP and set up your client, sign in to Gmail through the client and watch your messages arrive. You'll notice that all of your custom Gmail labels will appear in your client as folders, with your labeled messages inside. While we'd like to make your IMAP experience match the Gmail web interface as much as possible, some Gmail-specific features and terms, such as conversation threading and stars, won't appear in your client. Don't worry; you can still perform all the usual Gmail functions, just in a slightly different way. The IMAP behavior chart shows you how to perform common functions on your IMAP client.
After you perform certain actions in your IMAP client for the first time, you'll notice a few new labels when you next log in to Gmail's web interface. For example, sending a message in your client creates a 'Sent Messages' label in Gmail, indicating which messages you sent through your client and not through Gmail's web interface.
Some actions that will result in new Gmail labels are: creating drafts, sending and deleting messages, moving messages to a junk mail folder, and creating new folders in your client. Note that the specific names of these new labels will vary depending on which client you're using.
If you create folders within folders in your client, Gmail will treat these as separate labels. Gmail indicates which folder is a nested folder by adding a '/' before the corresponding label in the web interface.
Please note that some folder names are 'reserved' as special system folders in the Gmail web interface. If you attempt to create a folder name that conflicts with a reserved folder name such as 'Chats' or 'Sent,' these folders will display with an '[IMAP]' prefix ('[Imap]/Chats').
Furthermore:
Action on mobile device/client (e.g. iPhone/Outlook/Mac Mail) // Result in Gmail on the web
Open a message // Mark a message as read
Flag a message // Apply a star to the message
Move a message to a folder // Apply a label to the message
Move a message to a folder within a folder* // Apply a label showing folder hierarchy ('MainFolder/SubFolder')*
Create a folder // Create a label
Move a message to [Gmail]/Spam // Report a message as spam
Move a message to [Gmail]/Trash // Move a message to Trash
Send a message // Store message in Sent Mail
Delete a message in inbox** // Remove the message from inbox**
Delete a message from a folder** // Remove that label from the message**
Delete a message from [Gmail]/Spam or [Gmail]/Trash // Delete the message permanently
** Personal note: these actions do not actually delete a message. It acts similarly to archiving a message in Gmail (shown as "[Gmai]l/All Mail" in Mail application). As noted above, deleting a message from outside Gmail using IMAP simply "removes the label". Move messages to the trash folder which will then be deleted by Gmail's rules (default 30 days I believe). From an iPhone, "deleting messages" moves them to the trash on Gmails side (as what you would think would happen within Mac Mail). At least it did before.
If you use multiple email accounts with Mac Mail, the Gmail side will have its' own "section" with its own folders (labels) from the other accounts that are stored "On Your Mac".
If you only use Gmail with Mac mail, and have never previously set up Gmail to use with POP in it, then it won't be awfully confusing as when I did and got multiples of everything.
As far as Mac Mails Notes, if you go to Preferences, Composing, you can tell it to store Created Notes to the Gmail account, and the notes will basically get pushed to your inbox. Color settings are probably only reflected in Gmail but I don't know.
