User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7a) Gecko/20040209 Firebird/0.8.0+ Build Identifier: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7a) Gecko/20040209 Firebird/0.8.0+ When sending a mail outbound, when thuderbird communicates with the mail server it only declares the domain name on the "HELO" line. Eg: HELO aol.com This is pretty broken behaviour - many anti-spam solutions check this (at least on popular domains like yahoo, hotmail, aol, etc) to make sure the client's IP actally belongs to AOL's known relays. Thunderbird SHOULD use the name of the machine (preferably the hostname it has acquired from it's IP address). i could not find a more suitable catagory than "accounts maanger" for this bug :-/ Reproducible: Always Steps to Reproduce: 1. Send a mail 2. Look at mail server's log 3. Notice the HELO line. Actual Results: HELO was bad Expected Results: HELO should have been the FQDN of the machine.

Related: Bug 68877 Bug 68877 is for Mozilla, some UI would need to be ported

*** This bug has been marked as a duplicate of 68877 ***