I'm running Mercury/32 4.62 on my home computer testing phpBB3. So here's the input:
A) Some headers..
Date: Thu, 13 Nov 2008 01:40:01 +0100
Content-Type: text/plain; charset=UTF-8
X-AntiAbuse: Board servername - localhost
X-AntiAbuse: User_id - 1
X-AntiAbuse: Username - Anonymous
X-AntiAbuse: User IP - 127.0.0.1
B) Memory Core Process window
Pay attention to the < and > signs in the header's email addresses. whenever I try to send an email with a sender address of that format, I get an invalid sender address error in the Memory Core Process window like in the picture (this happened during 0:37 in.. picture time).
If I remove the <, > signs send operation completes successfully (during 0:48).
So, my question is who's nasty? Headers or Mercury?