[DebEtch/Postfix/MySQL/Courier: 571 when sending mail (first time)

Discussion in 'Server Operation' started by morenz, Mar 10, 2008.

  1. morenz

    morenz New Member

    Hi folks! ;-)

    My Server (Debian Etch Box built with Perfect Setup (plus some small modifies I added) with Postfix, Courier, MySQL, Amavis, ClamAV, etc...) is up and happily running since over a month (processing 200 mails per day).

    Today I sent an email (it's the first time I send an email to this recipient) with a 128KB PDF Attachment and I received the following response:

    571  MAIL REFUSED - Reverse DNS failed; cannot resolve the
        (perseo.mydomain.tld) domain in the HELO command. (in reply to end of DATA command)
    I verified Reverse DNS against www.mxtoolbox.com and got OK.

    I think it's not a problem of mine, because it's the first time it occurs in over a month of quiet uptime of the server.

    What could it be?

    Thanks in advance,
  2. falko

    falko Super Moderator ISPConfig Developer

    Please check the reverse DNS like this:
    dig -x [I][/I]
    where is the IP address of perseo.mydomain.tld.
  3. morenz

    morenz New Member

    Hi falko and thanks for the reply,
    I verified that my server has an outgoing public address of x.x.x.217 (address used by all machines, while the incoming address is NATted by the router on the x.x.x.218, so addresses do not match.

    Am I right?
  4. falko

    falko Super Moderator ISPConfig Developer

    Is it a public or a private address? It should be your router's public IP address.
  5. morenz

    morenz New Member

    yes, they are both public addresses, one (217) is the one we use to access Internet, the other (218) is the one that is assigned to the MX Record of my domain and that the router NATs to the mail server. I have to make an ip nat outside in the router to map the mail server to exit on address 218, not on 217 like all others.

    That's what I Suppose...

    Good night :)
  6. falko

    falko Super Moderator ISPConfig Developer

    What's in /etc/resolv.conf?
  7. morenz

    morenz New Member

    search mydomain.com
    nameserver 192.168.1.xxx
    nameserver has a private address because we have an internal DNS (2k3 server) that points to ISP DNS.

    ... another thing I forgot to say: we have 8 static IP assigned.
  8. falko

    falko Super Moderator ISPConfig Developer

    What happens if you use another name server?
  9. morenz

    morenz New Member

    That DNS points to ISP DNS, should I point directly to that DNS?

    Just a question (just because I always use to understand what I'm doing and why): how could a DNS change impact on my problem?

  10. falko

    falko Super Moderator ISPConfig Developer

    Maybe the name server you're using isn't working properly (or is caching for too long), and that might be the reason why the system can't resolve perseo.mydomain.tld.
  11. morenz

    morenz New Member

    OK, I will try using the ISP DNS and not the internal one.

    Thanks for now, I'll be back to report how did it work.


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