Can't reply to HTML email on 89.0b1 (64-bit) on macOS Big Sur


I’m using Thunderbird beta channel, currently running version 89.0b1. Installed using brew install thunderbird-beta.

I am having a problem replying to email from HTML view. To recreate:

  • Click on a received email that’s in HTML format
  • Click Reply or Reply All
  • Type in my reply
  • Click Send
  • The “Processing Message” dialog box flashes on my screen (it’s up for less than a second, so short I can barely tell what it says)
  • My reply is not sent.

I am able to work around the problem by switching to Plain Text view (View > Message Body > Plain Text) before I hit Reply or Reply All - if I do so, I can send the reply message without any problem.

This problem only happens when I am viewing a message in HTML view. It happens with both Original HTML and Simple HTML. If I view the message in Plain Text view, I’m able to send a reply message without any problems. Also - I have another machine on the same network that’s on 88.0b2 that does not have this problem.

It’s a really bad issue and needs to be fixed pretty quickly.