Exchange Server 2003 SMTP Issues

notcho67

5 pts.

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Exchange Server 2003

Microsoft Exchange Server

We recently switched ISPs and in doing so got assigned a different static IP address. That's when the problems began. Some emails go through without a hitch. Gmail for example delivers normally. There are others, however, that get hung up in the queue displaying errors like: "The connection was dropped by the remote host." "The remote server did not respond to a connection attempt." "Unable to bind to the destination server in DNS." Also, if I send the email on my phone using the same email address (but a different SMTP server, AT&T's) then it goes through fine as well. I used telnet to check port 25 and the connection and it works just fine. And like I mentioned, some mail goes through fine, but certain domains refuse to work properly. I have contacted Frontier (our ISP) and they said our Reverse Lookup was set up, but I'm not convinced as this looks like that sort of issue. Any suggestions?

Asked: November 15, 2012 8:55 PM Last updated: November 16, 2012 1:33 PM

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Harisheldon Nov 16, 2012 1:50 PM GMT

Just asking, but, have you done the following:Gone into your network connection, right click, go to properties, in the General Tab, highlight the Internet Protocol then click the Properties button, from there go to the Advanced button and click that, go to the DNS tab and ensured that the box for the Register this connection's addresses in DNS is checked? If not, check it and see what happens. Also, do you have the DNS suffixes in the proper order? I would think so since it did work before, but you may have to play with it since you have a new ISP.

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Gabe9527 Nov 16, 2012 3:36 PM GMT

OK I take it you do not use a third party mail gateway - such as Symantec.cloud (messagelabs)? this would mean you are connecting directly to the internet. If so do you have and SPF record associated with your domain.... this tell the recipient what address your mail is meant to be coming from (stopping spoofing). This may be the issue.Possible Telnet to the recipient server via port 25 this will also let you know if your IP is being blocked as you may have been added to a PUBLIC block (these are not liked by most SMTP gateways because of SPAM).Are you using TLS and if so is the return path the DOMAIN correct in DNS are this would mean the return lookup would find you sending from the wrong IP.

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