Review for ExQuilla for Exchange by Ari Meyer
Rated 4 out of 5 stars
Very good -- does most of what I need! When trying to set up a particular Exchange account as IMAP I had problems since the company apparently wasn't running an SMTP server, but this allows me to send mail!
One minor problem I have is that the "Save All" Attachments button/right-click does nothing, so I have to download multiple attachments individually. :-(
To create your own collections, you must have a Mozilla Add-ons account.