Is the Thunderbird-Firefox relationship getting you down? Does clicking links occasionally result in Thunderbird totally locking up for over a minute, before Firefox bursts into life with the requested page?

Apparently this started around Thunderbird v3, and here's how to fix it all the way up to v12:

  • Tools > Options
  • "Advanced" tab
  • "Config Editor…"
  • "I'll be careful, I promise!"
  • Set preference network.protocol-handler.warn-external.http to true.
  • Click on some link in an existing email
  • You now get the choice of which browser to use. Do not select Firefox. Instead, choose "Other" and locate firefox.exe on your hard drive.
  • "OK" everything.

Apparently Thunderbird works best when you pretend to it that its sibling Firefox is a third-party application that needs a simple shell invocation.