business email server Helo command rejected: Host not found;

Discussion in 'ISPConfig 3 Priority Support' started by gvvg, Aug 12, 2019.

  1. gvvg

    gvvg New Member HowtoForge Supporter

    Hi,
    I am hosting mail for a domain that is trying to receive mail from a valid domain.
    I think their email server might have some misconfiguration as I am seeing this message in the log:

    Aug 12 19:20:59 cpanel postfix/smtpd[13115]: NOQUEUE: reject: RCPT from mail.xxxxxx.com[xxx.xxx.xxx.xxx]: 450 4.7.1 <SRVMAIL.xxxxxx.com>: Helo command rejected: Host not found; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<SRVMAIL.so
    Since I know this is a valid business email server and it must be misconfigured is there a way to whitelist email coming from this server?

    Thanks,
    Gilbert.
     
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    Seems as if the hostname of that server is not configured in DNS. You can try to whitelist the server, but not sure if that will overrule the global hosts checks. if whitelisting does not work and you can't get them to configure their server name properly in DNS, then all you can do is to disable hostname verification globally in postfix main.cf. But this will increase the amount of spam that your users will receive.
     
  3. gvvg

    gvvg New Member HowtoForge Supporter

    Hi Till,
    Thank you for the explaination.
    I see in the /etc/postfix/main.cf
    smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, check_helo_access regexp:/etc/postfix/helo_access, reject_invalid_hostname, reject_non_fqdn_hostname, reject_invalid_helo_hostname, reject_unknown_helo_hostname, check_helo_access regexp:/etc/postfix/blacklist_helo

    From reading it seems like
    check_helo_access regexp:/etc/postfix/helo_access

    should allow me to whitelist a hostname just for the helo rejection due to the missing dns
    I have put
    /\[?72\.142\.2\.138\]?/ PERMIT

    in this file yet it doesn't seem to accept mail.
    Do I not understand the functionality?
    Should I just use the postfix whitelist function in ispconfig?
    I've got to figure out how to accept mail as there is no way to get in touch with their IT department, the client won't help - he says that how come we used to get their mail and now we don't.
    Thank you,
    Gilbert.
     
  4. till

    till Super Moderator Staff Member ISPConfig Developer

    I guess you might have to add the server hostname and not the IP in the helo whitelist file.
     
  5. gvvg

    gvvg New Member HowtoForge Supporter

    Thank you.
    Is there a method to whitelist the servername or IP from within ISPConfig?
     
  6. till

    till Super Moderator Staff Member ISPConfig Developer

    There is a whitelist in ISPConfig, but that's not for whitelisting helo.
     
  7. gvvg

    gvvg New Member HowtoForge Supporter

    Thank you Till.
    I got help from Florian to configure the helo_access file properly and now mail is coming through.
     
    till likes this.

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