My only current grief with Thunderbird is minor.

I recently circled about RSS feeds again and looked into "not Browser Addon" RSS clients - Feedbro as an extension is pretty good, has some shortcomings, and requires the browser to be left active 24/7 to catch ALL of a few of the feeds I follow.

Thunderbird accepts RSS feeds but, for better or worse, is extremely strict about only accepting fully compliant RSS | ATOM spec verified feeds.

There are a number of older "RSS feeds" that are compliant XML but missing a few recent feature fields - these work in Feedbro and other more accepting clients but fail in Thunderbird.

It's a minor quibble, I should write a note to the devs I guess, but it did dash my idea of having the one email+RSS feed hub active 24|7.