Outgoing SMTP E-mail 1

[Ashish2002]

Hello Guys,

This is a strange problem that I am having with my exchange server. It sends out all SMTP outbound mail, except the ones going to the .edu domain. I am not sure why it is doing that. I tried sending a message to user@cepo.conted.uah.edu also tried to send one to user@chla.usc.edu. These e-mails get queued and finally time out after two days. Is it because of the .edu domain of is it because the domain is too big like cepo.conted.uah.edu. Any help in this matter will be appreciated.

Thanks!
Ash

 

[FlyboyLDB]

I had this same problem except with certain .com addresses. I found that the ISP had something wrong with their DNS tables coming off of our domain name. If you are hosting your own DNS, then you may want to take a look at that, otherwise give the ISP a shout.

 

[xmsre]

Look up the MX record for the domain that is failing. From your exchange server, [if you have more than one in your environment, then the one that is the SMTP bridgehead] telnet to the server listed on the failing domain's MX record on port 25.

The error you get in the telnet session shoyld pretty quickly tell you if it's a connectivity issue, name resolution, or other issue. If you do a EHLO, MAIL, RPCT, DATA, etc. and manually transfer a message, the failure code should come back and tell you why. For example, 5.7.1 is typically a permanant error - connection refused. This often happens if the receiving end is doing a reverse lookup and your external DNS does not have a PTR record. Some places use whitelist and only accept from trusted senders. Others use blacklists of known open relays. There are many reasons other than DNS that can cause a connection to fail. The SMTP error code is what you need to figure out why.