Thunderbird 78+ TLS Connection Errors

Thunderbird 78+ requires TLS 1.2 by default.  Most of our mail servers support this out of the box, however, in case you receive an connection error that relates to TLS or SSL connections or just a general connection error it may be necessary to adjust an advanced setting within Thunderbird to set it to use TLS 1.1.  To do this, please do the following:

  1. Go to Thunderbird Preferences -> Advanced -> config Editor
  2. Search for security.tls.version.min
  3. Double click security.tls.version.min and a window should popup or the value box should be editable now
  4. Change the value to "2"
  5. Save the value
  6. Close and re-open Thunderbird

Thunderbird should now be connecting without an issue. 

We are migrating mail services away from the servers that this issue is coming up on.  If you would like to migrate before we hit your account in the migration list, please contact support. 

  • thunderbird, tls 1.2, tls, certificate, connection, error
  • 1 Users Found This Useful
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