Unable to recieve E-mail from one Customer

[Loren220]

Were experiencing an issue where one of our customers can not send us e-mails. Receiving e-mails from other customers no problem. We have our own exchange server in house. The customer is getting the error "retry timeout exceeded". I have enabled logging on our firewall and our exchange server but the only reference I see in the logs from their mail server is a block within the firewall for an IDENT request on port 113. I have checked our domain name on mxtoolbox.com and received all green marks. Customer IT department is stating the problem is on our end and we are blocking their mail server. Any advice on why this one client can't e-mail us?

Thanks,

 

[Zelandakh]

Just an outside chance of this but do you have any A records for your domain? If not, create one and see if they are using a reverse lookup that fails.

 

[Loren220]

Thanks for the reply. The customer allowed us to setup one of their e-mail accounts so I could conduct some testing. I think our MX records are hosed up. We have our own exchange server but another company houses our website. What I found during my testing is when an e-mail is sent to us from our customer it never passed or was blocked by our perimeter firewall. That sort of pointed me to our MX records as the issue. This is what I found regarding our mx records with mxtoolbox.com and dnsgoodies.com. Our domain name

http://www.testdomain.com

when checked shows MX, CNAME and A all pointing to our hosted website. When I only put testdomain.com then it shows the A record pointing to our hosted website and the MX pointing to our exchange. Is it possible that the customer mail server is sending mail to the hosted website?

Thanks,

Lo

 

[Zelandakh]

Nope.

Go home, telnet to yourdomain.com on port 25. Do you hit your perimeter firewall?

Also ping your yourdomain.com and note the IP.

Get that customerto telnet on port 25 and ping. Reckon you'll get differing results. Not sure why yet.

 

[Loren220]

I discovered that now two of our customers can not send us mail. Both customers have forwarded copies of their kick back messages to us and I noticed in the header that both customers are using EXIM version 4.69 and 4.74. I have been seeing IDENT requests coming from the customers mail servers and our firewall is blocking the request. Our mail server is exchange 2010 and is running on server 2008 r2. Do I need to setup an IDENT server to handle these requests in order to receive mail from EXIM mail systems? If so, what are these IDENT requests asking for?

Thanks,

Lo

 

[Zelandakh]

If your firewall is blocking the request, I'd say this is nothing to do with your Exchange server.