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New Member

SMTP HELO changed from hostname to IP

I've been trying to resolve an issue, but I'm having some trouble as I'm not very good with firewalls. My firewall seems to be changing information in the HELO command of SMTP traffic. It SHOULD look something like '220 ESMTP postfix'. Internal to my network, this works fine. However, external the received response is '220 [] ESMTP' which is my mail server's internal address (rather than it's external). This isn't an issue if I do a telnet to 465 (alternate SMTP listening port), only if I try to telnet (or connect) to 25. Does anyone know what could be causing this? I already removed my fixup protocol smtp 25 line from the config.


Re: SMTP HELO changed from hostname to IP


which firewall is this ?? can you please send us the static NATs/ACL configs ?? Are you able to see any translation happening on the firewall for ?? If translation happens, the outside world should see the packets only as the public IP !! Are you using a local DNS for to private IP ?? Is the same DNS talking to the internet DNS servers for name resolutions ??

Let us know


New Member

Re: SMTP HELO changed from hostname to IP


This is a PIX 515E v6.3(4). The mail server's internal address is actually, and it's name is ohio. I never set up this firewall; it was this way when I started working here.