Randy put forth on 3/24/2010 3:55 PM: > dig -x 208.43.143.111 > ;; ANSWER SECTION: > 111.143.43.208.in-addr.arpa. 3600 IN PTR > 208.43.143.111-static.reverse.softlayer.com.
Your problem isn't the Exchange server per se. Your problem is that you're forwarding spam to it, and its anti-spam software is better than that on your Postfix server, which causes the backscatter. Almost any mail coming to you from Softlayer IP space is going to be spam, most likely snowshoe. Softlayer is a generic ISP/COLO outfit with tons of resellers and terrible (non existent) customer vetting. They have few, if any, legit email sending customers. As you can see I've extensively SMTP blocked Softlayer over the years. I suggest you do the same. # Softlayer, Dallas 10/10/2008 66.228.112.0/20 REJECT 67.228.0.0/16 REJECT 74.86.0.0/16 REJECT 208.43.0.0/16 REJECT 174.36.0.0/15 REJECT 75.126.0.0/16 REJECT 173.192.0.0/15 REJECT Beef up the anti spam capabilities on your Postfix server and this problem will go away. Either that or tell the Exchange admin to silently drop/discard/eat the spam instead of rejecting it back upstream. The former is the preferable route, the latter the lazy route. -- Stan
