I have a mail server thats setup for virtual mail accounts. All of the email accounts created work just fine, except when they send email via the server it gets sent out as coming from emailaddress%domain@serverhostname.

Here is what the header looks like:

Return-path: <email%domain.com@serverhostname>
Envelope-to: test@domain.net
Delivery-date: Thu, 17 Jan 2008 12:57:04 -0600
Received: from [xx.#*$!.xx.#*$!] (helo=serverhostname)
by mail.thisserver.net with esmtps (SSLv2:DES-CBC3-MD5:168)
(Exim 4.68)
(envelope-from <emailaddy%domain.com@serverhostname>)
id 1JFZvA-0006aM-KK
for test@domain.net; Thu, 17 Jan 2008 12:57:04 -0600

Obviously I changed the IP and email addresses for security. The servers hostname is a fully qualified address (eg. mail.domain.com) if that makes a difference. I tried to google for this but without knowing what this type of behavior is called i couldn't find much. Any help or pointers are appreciated.