Issues with Thunderbird 78+

Mozilla disabled TLS 1.0 and 1.1 in the latest versions of Firefox and Thunderbird. Thunderbird 78 and above.

This causes issues with anyone connecting via SSL/TLS/StartTLS to us, as Qmail uses 1.0.

It can be enabled again through the menus of Thunderbird.

• From the menu at the top right, go to Options; on Mac it may be Preferences.
• Scroll all the way to the bottom and click on Config Editor.
• Skip past the warning.
• Scroll down until you find security.tls.version.min
• Double click on it, and set the value to 1
• Then okay it.
  

Close Thunderbird, and open it again; this should then have resolved the issue.

The following will also instruct you on how to access the Configuration Editor:

• Thunderbird v78, Config Editor: Windows 10
• Thunderbird v78, Config Editor: Mac
• Thunderbird v78, Config Editor: Linux