[gunnar]

I have my Mail accounts setup using IMAP and a my Sent messages are set to be deleted off the server every week so I don't exceed storage limits (I have a lot of mail with attachments). I have selected "keep copies of all messages for offline viewing" in the Mail preferences but after the week, the Sent mail is gone from both the server and my local computer. Is there a way I can ensure the sent messages are never deleted locally? I guess this would apply to my inboxes too.

[Cold Warrior]

offline viewing only caches them, it doesn't actually save them beyond the 1-week point that you specified.

If you want to really archive them to the local machine, you should either move them to a local sent items folder or configure your IMAP options so that sent messages are placed in a local sent items (not the sent folder on the server).

[gunnar]

How do I move them to a local sent items automatically?

[Cold Warrior]

I'd start by looking at Mail's Rules options, maybe it can move by date or age. I don't use Mail actively (really just when Apple releases major point upgrades to see if/how it's changed) but maybe someone else here has a specific workflow that does what you want.

[jrafter]

If you don't need a copy of your sent mail on the IMAP server, you should be able to have all your sent mail saved automatically—and indefinitely—in a local Sent Mail folder.

Mail > Preferences> Accounts > Mailbox Behaviors > [uncheck] Store sent messages on the server

[gunnar]

I need a copy on the server too because I want the same messages to be accessible from all the various computers...