I’ve used Mozilla Thunderbird as my desktop mail client of choice for years, switching from Microsoft Outlook because of its initially poor support for IMAP after I first switched from a POP3 to IMAP model for all my locally hosted mail accounts.

I’ve never really had many problems with automatic Thunderbird updates in the past, but the recent Thunderbird version 38.1.0 update caused me some major problems.

One of these was that it broke SSL connectivity to my Courier IMAP SSL service across all platforms – OS X and Windows. After a lot of digging I eventually found the cause of the problem was a tightening of security around key lengths and I had to tweak the dhparams.pem file in my Courier installation. This blog post discusses how to do this. After fixing this Thunderbird 38.1.0 was able to connect again over SSL.

The second problem was limited to OS X and this resulted in Thunderbird becoming unresponsive most of the time. Again after a lot of Googling I found that the cause was the Google Birthdays calendar configured in Lightning.After removing this calendar, Thunderbird became responsive again.

Hopefully this info might save someone else some pain if they experience the same problems.