Question : Sporadic Issue sending/receiving E-Mail

We are having sporadic issues with both sending and receiving E-Mail. I am trying to track down the problems however Im finding it difficult. I believe the issue has something to do with our DNS Setup. E-Mails will often time be delayed by several days before arriving at the outside company's e-mail server. These delay NDRs happen fairly often. Most times the emails get through though we have found that occasionally these delayed emails will arrive 30 - 40 times at the customer.

Background: We have Windows 2003 Servers/AD, Exchange 2003 SP2 and use Postini for Mail Spam/Virus Filtering. Postini is only on for INCOMING mail. Outgoing mail is sent directly from our organization.

Our company underwent a name change from Company A to Company B. Right now, and would like to keep, accepting e-mail from both companya.com and companyb.com. Everyone has 2 addresses but everyone is set to send from their [email protected] address.

Our domain name is still companya.com. I have not changed it yet to companyb.com but plan to in the future.

The Mail server is known as both its Mailservername and by Mail.companya.com name as reflected below in the DNS Settings.


Our outside DNS Settings are as follows:

companya.com
www                        A      111.100.100.10
@ (None)                  A      111.100.100.10
* (All Others)                  A      111.100.100.10
mailserver.companya.com      A      111.100.100.11
mail.companya.com            A      111.100.100.11

companya.com.postini1.com      MX
companya.com.postini2.com      MX
companya.com.postini3.com      MX


companyb.com
www                        A      111.100.100.10
@ (None)                  A      111.100.100.10
* (All Others)                  A      111.100.100.10

companyb.com.postini1.com      MX
companyb.com.postini2.com      MX
companyb.com.postini3.com      MX

There are no DNS records for servername.companyb.com or mail.companyb.com.

Because most mail gets through no problem, its tough to diagnose what our issue is. I just see the potential for problems with our domain name being companya.com when mail is going out with the *@companyb.com addresses. Maybe internal DNS is not setup properly? I can post that if needed. Neither domain has an SPF record.

Postini is set to just send emails to the public IP address of the server 111.100.100.11.

Anyone see any blatant issues?

Answer : Sporadic Issue sending/receiving E-Mail

The ISP does not need to host your DNS, but they do own your IP address, so they need to setup a Reverse DNS entry for your IP address and this needs to resolve in DNS back to your IP.

e.g., 10.10.10.10 - Reverse DNS = mail.yourcompany.com

DNS Check for mail.yourcompany.com should resolve to 10.10.10.10

Make sense?