I have a client that is using Windows 2008 SBS SP2 with Exchange 2007 that I installed about 2 years ago and it has been working great. Monday client, without informing me, decides to switch to ATT Uverse and calls me in a panic because nothing is working. When I arrive they have another tech already remoted into the server changing IPs to get their database program to work. He did not set DNS correct so I fixed that so server points only to its IP. I was rather unhappy about the whole thing as I don't like changing the network on a SBS server. Old network was 192.168.12.x and new is 192.168.1.x. So by Tuesday morning I get everyhting all resolved. I setup firewall to use one of the Uverse public IPs and open needed ports to the server on the new LAN of 192.168.1.x. Only problem now is that the server public DNS record for remote.mydomain.com is not correct yet. They contaced the guy to change it and he changed it to wrong IP and has not corrected it yet. Client has a strange setup - not my idea. They use POP email but use their Exchange server to send email and store it. Anyhow it was all working again fine by the time I left Tuesday morning after failrly extensive testing. Well late today Thursday client calls me again all in a panic as they can not send any email and are getting delay notices. So I remote in and find email in the QUE of Exchange 2007. I rebooted the server and it is the same. QUE is showing 451.4.4.0 errors. I run Exchange BPA and no problems found. So I use telnet and find I can NOT connect to ANY mail server via port 25 such as smtp.comcast.net. I can connect right away with port 587/80/26 that various email smtp servers use but NONE of them on port 25. I logon to another computer on the network and right away I can connect to any email smtp server on port 25 but NOT on the server?? The server has the Windows Firewall disabled and the service stopped, and no other firewall. Symantec Endpoint is installed but no firewall component. I disabled Symantec Endpoint for good measure and no change. I stopped ipsec service and no change. I rebooted the firewall (Linksys E1200 just for temporary) and no change. Anyone have any idea why this SBS2008 SP2 server suddenly can not connect to any smtp email server via port 25 or why the server can not even telnet into any?? It seems to be to me more of a server networking issue than an Exchange issue since I can not even telnet into any email smtp server via port 25 but can any other port. It did work fine for almost 3 days. Could this be an ATT Uverse issue?? They whole network uses the same public IP and other computers can telnet into email smtp servers on port 25 but not the server. This is my only client using ATT Uverse . The simple Linksys E1200 router has no sort of outbound traffic blocking enabled. I may try a different public IP on the Linksys E1200 router WAN side to try and see what happens. I think if I have to go to the client I also will reconfigure one of the network workstations to use port 25 for RDP temporarily and then see if I can telnet into that from the server. If I can it would appear to me it must be filtering via Uverse somehow. Thanks greatly for any help, tips, or experiences.

On the server open cmd and type telnet localhost 25 does it connect? If so your server is good and you need to start looking at your network\firewall logs. James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

Thanks for that tip!! Yes I can telnet into localhost 25 and it connects. At this point I am highy suspect of Uverse blocking port 25 outbound. Steve

time to get a network capture from the exch server and the firewall it goes out of, check both caaptures.Sukh

It was ATT Uverse blocking port 25 outbound even on a static public IP. It did not start out as blocked but for some reason they decided to do it a few days after install. All is good - for now. Beware of ATT Uverse!