SMTP MX Record proplem

[aultbmh]

We have a vendor of ours that we can't send email too. This is the only domain that we have issue with. Our email server is exchage 2003 on a 2k3 box. If I do a nslookup of the mx record for the domain we are having problems with we get the correct info. They have 2 entries with different costs. When our server trys to send an email to that domain it tries to send to the secondary mx record and that is only active if the primary is down. Email sits in the queue until it expires.

If I look at the SMTP logs that is where I can see it's trying to goto the secondary address

I'm wondering how or why the email server is trying to send to the secondary mx record???????

 

[aultbmh]

The domain we are having problems with is mochadata.com

 

[MSR63]

I just resolved a simular issue today. I had this issue since Thurs. when one of our companies who's on a POP server had issues with email. ATT made some type of configuration -- and tighten up everything..reverse DNS
We could NOT send them email at all - but could send to everyone else. We could also accept incoming mail from this company

It took me the entire weekend working with AT&T and my vendor on DNS suggestions - but neither helped. I finally had to contact my predecessor who took a look and said wahtever ATT did - it is not accepting our mail.

We had to change the reverse lookup to our exch name and domain on our mail server and finally they were able to get our emails.

Are you or this vendor - using ATT POP server?

 

[aultbmh]

No they are not using POP,,,,,we can receive email from them but can't send back to them sits in the queue until it times out (I think 4 days)

 

[58sniper]

What do the SMTP logs say? Looks like the MX record is correct, and the reverse DNS entry for the IP address is correct as well.

Pat Richard
Microsoft Exchange MVP

 

[Zelandakh]

If their server is not listening on the IP address then you won't get mail delivered and it will bounce back.

 

[aultbmh]

Here is the MX record lookup from our email server

> mochadata.com
Server: cldc01.complabs.com
Address: 192.168.4.61

Non-authoritative answer:
mochadata.com MX preference = 10, mail exchanger = mail.mochadata.com
mochadata.com MX preference = 20, mail exchanger = 2mx.integraonline.com

mochadata.com nameserver = ns36.worldnic.com
mochadata.com nameserver = ns35.worldnic.com
mail.mochadata.com internet address = 64.122.80.210
2mx.integraonline.com internet address = 204.130.255.6


And here is the SMTP log

2008-02-01 08:46:23 204.130.255.6 OutboundConnectionResponse SMTPSVC1 BL2K3SERVER21 - 25 - - 220+2mx.integra.net+ESMTP 0 0 25 0 203 SMTP - - - -
2008-02-01 08:46:23 204.130.255.6 OutboundConnectionCommand SMTPSVC1 BL2K3SERVER21 - 25 EHLO - bmail.complabs.com 0 0 4 0 203 SMTP - - - -
2008-02-01 08:46:23 204.130.255.6 OutboundConnectionResponse SMTPSVC1 BL2K3SERVER21 - 25 - - 250-2mx.integra.net 0 0 19 0 281 SMTP - - - -
2008-02-01 08:46:23 204.130.255.6 OutboundConnectionCommand SMTPSVC1 BL2K3SERVER21 - 25 MAIL - FROM:<@@@@@@@@complabs.com> 0 0 4 0 281 SMTP - - - -
2008-02-01 08:46:24 204.130.255.6 OutboundConnectionResponse SMTPSVC1 BL2K3SERVER21 - 25 - - 250+ok 0 0 6 0 375 SMTP - - - -
2008-02-01 08:46:24 204.130.255.6 OutboundConnectionCommand SMTPSVC1 BL2K3SERVER21 - 25 RCPT - TO:<@@@@@mochadata.com> 0 0 4 0 375 SMTP - - - -
2008-02-01 08:46:24 204.130.255.6 OutboundConnectionResponse SMTPSVC1 BL2K3SERVER21 - 25 - - 421+Service+unavailable,+please+try+primary+mail+exchanger+(#4.7.1) 0 0 67 0 453 SMTP - - - -
2008-02-01 08:46:24 204.130.255.6 OutboundConnectionCommand SMTPSVC1 BL2K3SERVER21 - 25 RSET - - 0 0 4 0 453 SMTP - - - -

 

[Zelandakh]

Your problem appears to be that you don't have port 25 open to the Internet. Can you telnet to the Exchange server on port 25 from inside?

 

[aultbmh]

Yes we can telnet to any other email server on port 25 on the server. The issue is for mochadata.com somehow even though if I do a lookup of the mx record on the email server and the info is correct. It tries to send to the secondary mx record and that mx record only works if the primary is down.

 

[Zelandakh]

Apols, misread. Can they telnet to port 25 from internal? I'm getting no response on either MX record.

 

[aultbmh]

From our mail server I CAN'T telnet to mail.mochadata.com but I can to the 2mx.integraonline.com so that is why it goes there. From my workstation I can telnet to either

from another client of ours I can telnet to either one so what would block telnet to the primary mx????

 

[dixson]

Do you have a firewal installed somewhere in the link? can you have a look at the firewall logs?