Rated 3 out of 5 stars

For smaller mail accounts this should work just fine, but when you're running with a larger mailbox with 15-30 subfolders and quite a few archived messages this thing begins to slow to a crawl. For comparison IMAP is able to handle the load just fine(2-8% CPU usage on average), though my office only allows exchange protocol outside the office network so I deal with ExQuilla.

The license cost is worth it, a project like this doesn't grow on trees. Evolution works, but isn't cross-platform like Thunderbird(the evolution ports are no longer developed).

This review is for a previous version of the add-on (38.0.1159.1-let-fixed).