This has been reported as Bug #1060901. If you have an account on Bugzilla, please consider voting for that issue.

Several other people have sent in the same support request as you, noting this happened after they upgraded to version 31.1.

The exact error message is: XXXX is not a valid e-mail address because it is not of the form user@host. You must correct it before sending the e-mail.

This happens in Thunderbird 31.1.0 when your mailing list description includes several words separated by spaces.

Although not ideal, these workarounds should let you use your mailing lists until a proper fix is implemented:

• While composing an email open the address book and select the list you are trying to send to, highlight all the names in the list and drag them to the To: box. This uses your existing data without modifying it.

• Replacing the blanks " " between the words in such lists' descriptions with an underscore "_". This requires modifying your mailing list(s) description(s).

• Downgrade to a previous version and disable automatic updates (Windows)

About automatic updates

Automatic updates are the default in Windows.

You can customize such behavior, however, it's under Tools > Options > Advanced > Update.

My suggestion would be to set it to Check for updates, but let me choose whether to install them., specially if you depend on email for critical / important business or personal matters.

I used the second option and it worked like a charm! Thank you so very much!

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

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