I access email on several devices and want to archive messages on all of them -- particularly on my primary computer. This has worked fine with a POP3 account; I configured TB to keep emails on the server for a few days, by which time I could download them on all devices. But now I've switched to Microsoft Exchange as my email host, where POP3 isn't an option. I tried setting up the new account as IMAP in TB, which worked to send and receive messages. I also tried using a plugin for TB called ExQuilla that lets you set up TB specifically for Exchange. The problem is that with either setup, my messages are deleted from the Microsoft server as soon as I download them. There's no setting on TB (with IMAP or Exchange) that lets me decide whether, or how long, to keep the messages on the server. Microsoft tech support claims the problem isn't with their server - and that they don't know enough about TB to help.

Any ideas for how to make sure my messages aren't deleted from the server the first time they're downloaded by TB?