Hi,

My Frontend Transport server is placed behind a firewall which uses NAT to forward port 25 to it. The following is a sample of the header of incoming email from external source.

Received: from verifier.port25.com (xxx.xxx.xxx.xxx) by myserver.local (a.b.c.d) with Microsoft SMTP Server id 15.0.1044.25 via Frontend Transport; Wed, 8 Apr 2015 17:55:27 +0800
Received: from verifier.port25.com (127.0.0.1) by verifier.port25.com id h4jtgu20i3gm for <recipent@domain.com>; Wed, 8 Apr 2015 

Note the (xxx.xxx.xxx.xxx) is my WAN IP instead of the actual IP for verifier.port25.com, most likely due to the fact that the Frontend Transport is behind the NAT firewall (I'm using Centos 7 with iptables). How do I fix this?

I believe for Exchange Server 2003, the solution is as shown in http://www.exchangeinbox.com/article.aspx?i=44. However, I can't find any such configuration for Exchange Server 2013.

Thanks.

Hello,

Thank you for your post.

This is a quick note to let you know that we are performing research on this issue.

If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com