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  1.  Home
  2. PCTECH
  3. November 2009

SMTP: helo != ptr?

I just observed a slightly odd smtp conversation from my mail server to another ...

220 R2D2.example.com ESMTP ready at Mon, 16 Nov 2009 10:13:40 -0500
EHLO mail.midrange.com
250-R2D2.example.com
250-SIZE 20480000
250 8BITMIME
MAIL From:<bpcs-l-bounces+user=example.com@xxxxxxxxxxxx> SIZE=4201
421 R2D2.example.com has refused your connection because your HELO string did not match your PTR record
QUIT

I'm curious ... does anyone know of a RFC or other requirement that specifies that the helo host value match the PTR dns value?

Or is this just an overly aggressive mail admin?

I can understand where a PTR record might be required.

david


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