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List:       postfix-users
Subject:    Re: Refuse mail from hosts with closed port 25
From:       "Bill Cole" <postfixlists-070913 () billmail ! scconsult ! com>
Date:       2019-09-16 13:59:51
Message-ID: C0754889-0491-4204-A0D2-2D3185CA9F45 () billmail ! scconsult ! com
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On 16 Sep 2019, at 9:17, Kevin A. McGrail wrote:

> On 9/16/2019 9:03 AM, Jim Reid wrote:
>> On 16 Sep 2019, at 13:47, Paul van der Vlis <paul@vandervlis.nl> 
>> wrote:
>>
>> How can I refuse mail from hosts who don't have an open port 25?
> Paul, I wrote a module which I need to update on Perl's CPAN called
> Net::validMX that we use to reject IPv4 domains that aren't properly
> setup to receive mail from sending to us.  We've used it in 
> production
> with MIMEDefang.  And as a small, boutique ESP for over a decade, 
> likely
> closer to 15 years with no complaints/FPs of note.

I don't believe that Net::validMX does anything more *at the domain 
level* than Postfix's built-in reject_unknown_sender_domain restriction. 
Its check_email_validity() may be a bit more strict than Postfix's 
built-in address sanity checks.


-- 
Bill Cole
bill@scconsult.com or billcole@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
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