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Blocking spammers based on SMTP HELO command

Stewart -

Spammers are abusing my machine.


  • On-Premise Server + WebMail Installations: Version 6.0 > Current Version

If you are noticing a spammer is abusing your machine which is identifying with a common "HELO" command via SMTP, you can optionally deny all messages which match this rule.

For example a spammer might be identifying to your server with a fake HELO command which is common for all SMTP transactions.


  1. Edit /usr/local/atmail/mailserver/configure
  2. In the ACL
  3. You can append the new rule below for the HELO check
    deny message = HELO not allowed
    condition = ${if eq{$sender_helo_name}{}{yes}{no}}
  4. Copy the rule for each domain you wish to check.
  5. Restart the Atmail services and the new HELO check is live.
    # telnet localhost 25
    Connected to localhost.localdomain (
    Escape character is '^]'.
    220 Welcome to the @Mail SMTP Server ( Exim )
    250 Hello localhost []
    mail from:
    250 OK
    rcpt to:
    550 HELO not allowed



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