Technology / 

27 Oct 2007

Some Notes on Gmail's New IMAP

A few days after they started rolling it out, the Google Gods finally saw fit to smile on me and grant me the gift of IMAP. And, oh, what a gift it is. Gmail and IMAP are two systems that just seem made for each other, and despite some oddities, I’m shuddering just thinking of POP.

However, I have noticed a few interesting caveats with Gmail. These apply to Gmail as of 10/27/07 used with Apple Mail 2.1.

• You will get many copies of the same outgoing message in your “All mail” folder/store on Gmail, if you have the “Store draft messages on server” option (in Preferences:Accounts:Mailbox Behaviors) set. Basically, every time Mail sends a new draft version to the server (which seems to happen about once a minute or whenever you pause typing), Gmail interprets this and stores it as a new message, which will appear in your “All mail” view. For some people, this might be a feature – looking back, you can actually see the process of composing all your messages. But for most of us, I think it’ll just be clutter and take up space. Better to leave it off.

• You will get duplicate sent messages if you have “Store sent messages on server” checked. This option isn’t necessary as long as you’re using Gmail’s outgoing SMTP server to send messages – you can feel free to uncheck it, and you’ll still get sent messages in your “Sent Mail” folder/view. If you have it checked, when you send a message, Mail will send it twice: once via SMTP, and then it will upload it via IMAP to a ‘Sent Items’ folder that it creates itself (which is not the usual Gmail ‘Sent Items’ view). Since Google is unusually smart and intercepts the outgoing SMTP message, you don’t need the second IMAP copy. Therefore, you probably want this off.

• If you don’t want to mess with Google’s folder structure, turn “Store Junk messages on server” and “Move deleted messages to the Trash mailbox” off also.

• There is no way in Apple Mail to switch an account from POP to IMAP. You just have to delete or mark the POP one as inactive, and then create a new IMAP one. (You may want to back up the POP one first, since deleting it will erase all mail stored under that account on the local system.) At the very least, make sure the IMAP one is working and fully replicated locally before you delete the POP account.

• On all machines except for your main one (and possibly even that one, if you trust Google a lot), you probably want to change the “Keep copies of messages for offline viewing” option on the “Advanced” tab. By default it’s set to download and mirror all mail in the IMAP account, which could be several GB if you’ve had Gmail for a while. For a laptop or other mobile system, you may want to consider “Only messages I’ve read” as an alternative.

• Google seems to do something funny to message attachments, but I’m not clear exactly what. I send all digitally-signed email (generally S/MIME), and I’ve noticed that outgoing messages that I send, which have attachments and are digitally signed, come up with invalid-signature errors when I view them later in my Sent Mail box. (However, they go out fine, and the recipient gets them without errors.) Google is changing something in the message – perhaps the names of the attachments or something – that is causing the signature verification to fail. Be aware of this if you use digital signatures with your Gmail account.

Anyway, that’s all I’ve noticed so far. Mostly just little things; it’s a great improvement to the service overall.

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