5

When sending out emails with postfix I sometimes get this error:

451 #4.1.8 Domain of sender address <[email protected]> does not resolve 
(in reply to MAIL FROM command)

The domain mydomain.tld is resolvable though, meaning A, MX, PTR records are set properly.

However, the sending server does have a different domain anotherdomain.tld but it is allowed to send emails from mydomain.tld since I set the MX records of mydomain.tld to anotherdomain.tld. The envelope from of the problematic emails is [email protected].

Is there some other dns entry I have to set?

Or how else could I solve the problem? (I would like to keep the server structure though)

4
  • As womble says, it's very hard for us to offer any real information while you redact the domain in question. DNS is a public resource; I urge you, and authors of similar questions, not to redact domains in such questions.
    – MadHatter
    Jul 23, 2012 at 12:02
  • @MadHatter: You are right. However I may not publish the domain name here unfortunately...
    – horen
    Jul 23, 2012 at 12:16
  • Whoever says that is foolish. You'll have this problem until you fix it, and being open about the domain name is likely to get the problem fixed more quickly. So ask whoever says that whether they prefer to be a little embarrassed but have working email, or save face but have non-working email. Though I'm not even sure why they'd be embarrassed; we all have stuff break all the time, you're not the only ones!
    – MadHatter
    Jul 23, 2012 at 12:23
  • Check to see if your domain has expired. Was the case for me.
    – Joe Karuri
    Feb 24, 2016 at 12:40

1 Answer 1

4

The problem is simply one of DNS resolution. Either the receiving MTA doesn't have reliable DNS resolution, or your DNS servers are flaky. Without knowing what domain mydomain.tld actually is, it's impossible for anyone to determine whether the latter is the case, but the more recipient domains who are sending you this error, the less likely the former becomes.

5
  • so you think the problem isn't that anotherdomain.tld is sending with the envelope from [email protected] but that anotherdomain.tld does actually not resolve? which dns entry does that error msg actually mean - is it the A RECORD? If it would be the A record of mydomain.tld, it would obviously not point to the IP of anotherdomain.tld - maybe that's the problem?
    – horen
    Jul 23, 2012 at 11:28
  • In short: No. ANY. No.
    – womble
    Jul 23, 2012 at 11:39
  • @adaptr: What does Postfix's resolver have to do with this problem? It's an error from the recipient MTA.
    – womble
    Jul 23, 2012 at 12:42
  • I re-read it and deleted it, sorry.
    – adaptr
    Jul 24, 2012 at 9:42
  • 1
    I was able to fix it by changing the DNS entries for the MX record. I debugged using the dig command. It returned ;; Truncated, retrying in TCP mode instead of a valid answer. Now everything is fine
    – horen
    Jul 27, 2012 at 8:00

You must log in to answer this question.

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