Sync On Arrival 1.3 Requires Restart
by Michael Buschbeck
Downloads new message headers (and bodies, if configured) immediately when Thunderbird detects new messages in an IMAP folder - that's more or less what the "download_on_biff" preference promises to do, but somehow fails to deliver...
About this Add-on
As an additional benefit, this keeps Saved Search folders up-to-date in IMAP accounts even if "search online" isn't checked. Very handy if you have a Saved Search configured to show all of your unread email.