Today I have faced the following one of my team have received a message today with following header internally via our mail server from the mail account name user_xyz@domain.com, How can I make sure that its been sent from that account and the IP? Why I see TimeoutProtection in the header?

X-Symantec-TimeoutProtection: 0
X-Symantec-TimeoutProtection: 1
Return-Path: user_xyz@domain.com
Received: from imail.domain.com (LHLO imail.domain.com) (10.5.1.10) by imail.domain.com with LMTP; Thu, 4 Oct 2012 10:01:41 +0300 (EEST)
Received: from localhost (localhost.localdomain [127.0.0.1])
by imail.domain.com (Postfix) with ESMTP id 6C9D02DC1F7;
Thu, 4 Oct 2012 10:01:38 +0300 (EEST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: 0
X-Spam-Level:
X-Spam-Status: No, score=x tagged_above=-10 required=6.6 tests=[]
Received: from imail.domain.com ([127.0.0.1])
by localhost (imail.domain.com [127.0.0.1]) (amavisd-new, port10024)
with ESMTP id ySPfzr67W6bz; Thu, 4 Oct 2012 10:01:35 +0300 (EEST)
Received: from Host_station (unknown [10.6.1.50])
by imail.domain.com (Postfix) with ESMTP id 518F12DC1F3;
Thu, 4 Oct 2012 10:01:33 +0300 (EEST)