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My Server is sending Registration-Success-Mails to our users. Most of them arrive, but recently one E-Mail to a specific domain remains in the mailq with the following error

(host smtp.geofs.de[5.45.103.59] said: 
450 4.7.1 <Ubuntu-1004-lucid64-minimal.localdomain>: 
Helo command rejected: Host not found (in reply to RCPT TO command))

Some answers i found here suggested to remove the config parameter "reject_unknown_helo_hostname" in "smtpd_helo_restrictions" but as it turns out my main.cf does not even have "smtpd_helo_restrictions" set. Is there a default value somewhere? Where can i change it? Is there another possible problem-solution?

Here is my current configuration in /etc/postfix/main.cf

# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no
myorigin = /etc/mailname
mydestination = xxmydomainxx.com, Ubuntu-1004-lucid-64-minimal, localhost.localdomain, localhost, xxmydomainxx.de
relayhost = 
mynetworks = 127.0.0.0/8 xxx.xxx.136.32/27
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
home_mailbox = Maildir/

Is the problem caused by my server or the receiving party server? And how can i fix it?

Love to hear your Ideas, Thanks!

1 Answer 1

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(host smtp.geofs.de[5.45.103.59] said: 450 4.7.1 :

the restriction is set on the receiving server smtp.geofs.de . The message is rejected because the sending (=your) server uses a non-resolvable HELO "Ubuntu-1004-lucid64-minimal.localdomain".

Either fix your hostname system-wide or set a resolvable helo in your postfix configuration ( myhostname )

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  • 2
    fixed it by adding myhostname=xxmydomainxx.com to the /etc/postfix/main.cf - Thanks!
    – patrics
    Apr 28, 2014 at 10:47
  • 1
    You should also make sure that the reverse DNS of the server matches the forward server. That is, nslookup <serverip> matches the domain name you have put into myhostname Apr 28, 2014 at 15:14

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