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A strange problem recently developed with one of my Exchange 2010 servers. I have an exchange server setup as part of a Windows Small Business Server 2011 installation. The email for the domain was working perfectly for 4 or 5 months, and now with no change in configuration is having problems.

The inbound email still works great, but when an email is sent it occasionally bounces back with one of several error messages. It doesn't happen to all of the sent emails, just some of them. It appears as though mail sent to certain domains will always bounce, including mail sent to domains that used to work. It also seems like the error message is generated by the recipients receiving server. Here are some of the error messages that bounce back:

host123.SomeEmailHost.com rejected your message to the following e-mail addresses: Someone LastName (aperson@adomain.com)

host123.SomeEmailHost.com gave this error: Verification failed for The mail server could not deliver mail to sender@sendingdomain.net. The account or domain may not exist, they may be blacklisted, or missing the proper dns entries. Sender verify failed

A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

Here is another message received when sending to a different domain:

mail12.anotherhost.com rejected your message to the following e-mail addresses: someoneelse lastname (someoneelse@anotherdomain.com)

(someoneelse@anotherdomain.com) mail12.anotherhost.com gave this error: sorry, that address is not in my list of allowed recipients; no valid cert for gatewaying (#5.7.1)

A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

I have tried researching these errors, but have not turned up anything that seems applicable to my server. Is it some sort of certificate error. I am using a self signed certificate on the server. If that is the problem, why did it just now start being a problem?

Any insight would be greatly appreciated.

  • Do you have a PTR record configured for your outgoing IP for the Exchange server? – Vick Vega Oct 16 '15 at 14:50
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Have you tested to see if you mail domain has been blacklisted? Another reason could be because the recipient is looking for a SPF dns entry for you domain. Have you created a SPF account?

  • I did a test to see if the domain is black listed. The test I ran checked in over 50 of the most popular black lists. It was not black listed in any of them. The domain does not have SPF records, I thought about it that that might be the problem. I will need to give that a try. – ThinkerIV Jun 26 '12 at 15:47
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Recipient mail servers do a reverse DNS check to verify if the ip address from which the mail is being sent is authorised to do so. The recipient mail servers query the DNS to fetch the SPF and DKIM. These entries tell the recipient mail server the ip addresses that are authorised to send out email on behalf of the domain. Ideally creating a SPF for your domain should solve your problem.

If you have operated your email server without a SPF entry chances are that your ip has made it to one of the several blacklists. Use the mxlookup (google it please) and check the if the ip is listed and have your ip removed. The removal procedure is different for each of these lists.

  • You should laso consider creating a DKIM (Domain Keys Identified Email) record on your DNS. Some email servers look for DKIM. – sridhar pandurangiah Apr 21 '17 at 7:20

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