I am having trouble with a newly installed server that we have just migrated to. I am running sendmail and cannot send mail to a specific domain. Mail everywhere else appears to work. Logs say:

DSN: Service unavailable

Weirdly, I get a Message accepted for delivery and then a following entry to say DSN: Service Unavailable.

Why would this be? I do not have it relaying through a smart host. The server that I am sending from does not have a public IP and is purely for sending mail from a PHP application.

Any advice appreciated as Google hasn't been a big help.

  • Do you have something else in your logs?
    – dave
    Aug 23, 2012 at 12:33
  • I suspect you don't actually know what DSN means. Sendmail is telling you that it tried to send the message using the ESMTP extended syntax, but the remote server didn't like that.
    – adaptr
    Aug 23, 2012 at 12:37
  • 1
    One possibility: the remote server thinks you're spamming, or is greylisting you.
    – cjc
    Aug 23, 2012 at 13:24
  • Are you sure you don't mean DNS? A DSN is something used to connect to databases. It's not a service. Aug 23, 2012 at 14:17
  • DSN can also stand for Delviery Status Notification (RFC 3461 - tools.ietf.org/html/rfc3461)
    – dunxd
    Aug 23, 2012 at 15:18

1 Answer 1


It might have mx record setup issue. Run the following command:

dig site.com mx

where site.com is your domain name.

In the output you will see Question section it is question to find the MX. In answer section you will find the mx entries configured for the domain. Check the mx records if they are correct.

Sample output is given below: where there 3 mx record entries like ASPMX.L.GOOGLE.com., ALT1.ASPMX.L.GOOGLE.com. etc

;; QUESTION SECTION: ;thestarworks.com. IN MX

;; ANSWER SECTION: thestarworks.com. 3600 IN MX 10 ASPMX.L.GOOGLE.com.
thestarworks.com. 3600 IN MX 20 ALT1.ASPMX.L.GOOGLE.com.
thestarworks.com. 3600 IN MX 30 ALT2.ASPMX.L.GOOGLE.com.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .