Unable to obtain any valid MX records for the domain.

[aluisi]

The title says it all. I just changed around my firewall set everything on nat and give my web/email server a static NAT ip. The old IP of the web-server is now the WAN IP of my firewall. Our site is working fine from the out side. I can access the Admin as well as the web-mail from the out side. But for some reason now when we try to send emails it sits in the out going mail queue. After the time set for the queue has passed I get a email back stating "Unable to obtain any valid MX records for the domain."

This just started happening today. We were receiving and sending email yesterday and Now today we cant get or send anything at all. Am i missing something when it comes to the ports? I have the smtp and the pop3 set as any source coming in on these ports to forward it to the server IP. I checked and it is getting our DNS info.

[aluisi]

Okay i figured out what the problem was. I checked everything when it came to port 25. My server my firewall everything was configured and allowing connections to that port. When I tried to connect on that port to the ability mail server it either timed out or refused connection to that port. I started to turn off my SPAM filtering since I narrowed down the problem to the Ability Mail Server. I turned on all the SPAM filtering except the Gray List, all my connection issues were resolved. The Gray Listing is stopping connections to port 25 to my ability mail server. I think this is a issue you all at code-crafters should start to look at. My mail server was fine and worked for a while when i had gray listing enabled but it eventually started to slow down to almost a dead stop then refuse connections to port 25.

[rob]

Glad to hear you found the source of the problem. Grey listing, although an excellent method of catching mail, does directly interfer withing incoming mail and initially refusing mail (then allows through later). This aggressive method is intended to deflect send and forget mail delivery agents, which basically do not retry, where as almost all real SMTP systems retry for a certain amount of time. This means it can only affects the SMTP incoming mail. This shouldn't effect the MX lookup ability of outgoing mails. Although disabling the grey list for you do sound like the best course of action for your setup, I would recommend checking your outmail log to see if mails are still sending correctly.

[gretchendv]

I'm getting the same error. My only change was to implement the Bayesian filter. Now when I send a company wide email I receive a list of email addresses with the message "Unable to obtain any valid MX records for the domain." No all of the email addresses have this problem. I looked at the settings of the accounts for whom delivery failed as well as those who successfully received my email. I was unable to determine a pattern. Any ideas as to how to address this problem?

[gretchendv]

Okay, I figured it out. I think the error had nothing to do with the Bayesian filter. I sent my email using an outlook distribution list that I haven't used in a long time. While importing the email addresses into my distribution list, Outlook put single quotes around the email addresses. These single quotes appear to be the cause of the problem. I removed the single quotes from the affected email addresses and the email was delivered successfully.

[fiver]

Last week I implimented the Bayesian filter on my server to combat the growing number of Spam messages coming through my server. I have recevied a query from a person who regularly sends mail to accounts on one of the domains I host, and he tells me that he too is receiving this message when trying to send mail to accounts on my server. This does not appear to be happening to everyone and would appear to be intermittent.

Have you any idea what may cause this and so rectify the problem.

Many thanks

Ivor

[rob]

Fiver if you could send me a copy of the error message/mail the user is receiving to rob@code-crafters.com it will finding the source of the problem.