[Mailman-Users] All confirmation emails going to SPAM on gmail

[Stephen J. Turnbull]

Nitin Sharma writes:
 > On Thu, Sep 3, 2015 at 7:01 PM, Mark Sapiro <mark at msapiro.net> wrote:

 > > Received: from ip-10-73-187-221.ec2.internal (mail.nypny.com.
 > > [2001:470:1f07:12b5::2])
 > >         by mx.google.com
 > >
 > > which I think says your MTA identifies itself in EHLO as
 > > ip-10-73-187-221.ec2.internal and not as mail.nypny.com. This
 > > could make a difference.
 > 
 > That was it. I didn't think that would make much of a difference, but
 > I changed the EHLO and it is no longer spam.

This actually is huge.  Any indication that your mail was handled by a
machine with a dynamically assigned IP is going to bump your spam
points by quite a bit.  The IP itself is impossible to connect to your
domain, because IPs that start with 10 are not on the Internet.  Those
IPs are defined to be for internal use only (as the rest of the
original EHLO domain also hints).

Tell your friends and colleagues! :-)