The End-To-End Internet (was Re: Blocking MX query)

John Levine johnl at
Wed Sep 5 23:07:07 UTC 2012

>Well, if you've got proper forward and reverse DNS, and your portable 
>SMTP server identifies itself properly, and you are using networks that 
>don't filter outbound port 25, AND you have DKIM configured correctly 
>and aren't using it for a situation for which it is inappropriate, then 
>you'll get the same results with a portable SMTP server that you would 
>sending through a properly configured static server.

Not really.  Large mail system like Gmail and Yahoo have a pretty good
map of the IPv4 address space.  If you're sending from a residential
DSL or cable modem range, they'll likely reject any mail you send
directly no matter what you do.


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