In order to connect to an U-M Google Mail account using an IMAP client (e.g. Microsoft Outlook or Apple Mail), a user must first enable IMAP Access to the account using the browser interface:
Now that IMAP Access has been enabled for the account, ensure that is configured properly for the user depending on if they plan to Archive or Delete. Under the Enable IMAP button, you will see two more sets of radio buttons. The first set determines whether messages marked for deletion on the client should "Auto-Expunge." The second set determines whether expunged messages should actually be archived, moved to Trash, or truly deleted forever. By default, these buttons will be set to Archive messages, as shown below:
If the user wishes to Delete instead of Archive, they will first need to click the button to turn Auto-Expunge off. Once that is selected, the next set of radio buttons will become active, and the user can now select whether to move messages to Trash or delete them immediately. Messages moved to Trash will be automatically deleted from the server after 30 days.
What is Auto-Expunge?
The IMAP protocol allows messages to be "marked for deletion;" a sort of limbo state where a message is still present in the folder but is slated to be deleted the next time the folder is expunged. When IMAP Access to Google Mail was launched, Google thought it might confuse users to have messages in this state, since it's not available in the web interface. So in Google's IMAP implementation, when you mark a message as deleted, it doesn't linger in that state -- it deletes it from the folder completely. Google calls this "Auto-Expunge."
Deleters will need to hide the All Mail folder from their IMAP client. All Mail is always the last visible IMAP folder, since it is where archived messages are viewed (i.e. messages with no labels):
Note that now the user will not be able to archive messages, since All Mail is invisible and they won't be able to move messages to it via IMAP. All Mail will still be accessible via the web interface.
Starred and Important are System Labels specific to Google Mail. Stars are used to mark special messages with a visual reminder via the Google Mail web interface. Importance markers are automatically added to messages by Google Mail to designate which ones it thinks are important to you. These behaviors are not compatible with most IMAP clients. It is recommended to uncheck the Show in IMAP boxes for these Labels (as described above for All Mail) so they do not appear in the IMAP client's folder list.
Maximum of 10 simultaneously IMAP connections
Google limits each account to 10 simultaneous IMAP connections (access via the browser does not count). This may sound like a lot, but many clients like Apple Mail can establish up to four IMAP connections per instance. The iPhone Mail app can also establish multiple IMAP connections when running. So, if a users is checking Mail via IMAP on their laptop and is also running Mail on the iPhone in their pocket, they're already using over half of the allowed IMAP connections. If they then happen to open another client (e.g. on their desktop or tablet), they'll likely exceed the connection limit. Google will automatically block the most recent IMAP connection until the total number of connections drops below 10, and even then the user may have to wait 10 minutes (Google's IMAP timeout period for inactivity).
IMAP Bandwidth Lockouts
Google Accounts only provide a limited amount of bandwidth, as described on their Bandwidth limits page:
Users who exceed these limits will have their accounts locked for 30 minutes. Users can unlock the account earlier by visiting the following URL: https://www.google.com/a/umich.edu/UnlockCaptcha
* IMAP translates labels with a forward slash (/) into a folder hierarchy. If you have a label such as "Family/Friends," the IMAP client will display it as a folder named "Family" with a subfolder named "Friends."
** When you delete messages in IMAP clients, it removes the message from your Inbox, but doesn't permanently delete the message.
Related Google Support Links