User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:15.0) Gecko/20100101 Firefox/15.0.1 Build ID: 20120905151427 Steps to reproduce: First I tried to send an email. Then I got and dismissed your alert message: "An error occurred sending mail. The mail server sent an incorrect greeting: [IP address] has not been authenticated to relay mail. Connect to your mailbox before sending mail via this relay." So I read mail. While mail was incoming, Thunderbird sent the email I'd been trying to send. My "Sent" mailbox records that it was sent. No mail window remained open. Actual results: The recipient did not ever receive the email. So, I think your client has a serious bug. Expected results: Your sent interface should never record as sent any piece of information that wasn't really sent.

can you easily reproduce ?

Yes, I'm afraid so. (Sorry for the delay. I have to wait over an hour until I can get that alert. Sending to myself failed in exactly the same way.)

Hi gentlemen. Just a follow up note. The first thing I did today was send my husband an email. He did not receive it. But Thunderbird says it sent it. So I think this is a serious bug. Do you?