User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; de; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14 Build Identifier: Version 2.0.0.14 (20080421) Code from Source --- snip --- From: =?iso-8859-1?Q?M=F6ller=2C_Angelika?= <Moeller@XXXXXXXXXXX.de> To: =?iso-8859-1?B?SuRrZWw=?= <jaekel@XXXXXXXXXX.de> --- snap --- is shown as you can see in Screenshot http://xp8.de/TB-BugIsoFrom.png. I Think it´s a problem of the "=2C_" string in the iso-encoded from-string. Reproducible: Always Steps to Reproduce: 1. a "from" in an eMailclient that produces this: From: =?iso-8859-1?Q?M=F6ller=2C_Angelika?= <Moeller@XXXXXXXXXXX.de> 2. send the mail 3. recieve and open it in Thunderbird 4. you will see TWO "from"´s 5. reply 6. you will see that thunderbird replys to both adresses Actual Results: see that thunderbird replys to both adresses a) Möller b) Angelika <Moeller@XXXXXXXXXX.de> Expected Results: reply to "Angelika, Möller" <Moeller@XXXXXXXXXX.de> could be a security problem - if i write a mail with a spurios sender that results in replying the mail to originalsender AND to the attacker.

The mail spec, at least old rfc 822, allows multiple authors to be listed in From headers. I'll leave this for the mail guys to determine if we're treating this case correctly, but I don't see how it could be a security issue.

This is bub 254519.