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List:       postfix-users
Subject:    Re: Refuse mail from hosts with closed port 25
From:       Chris Wedgwood <cw () f00f ! org>
Date:       2019-09-17 0:16:38
Message-ID: 20190917001638.GB30303 () aether ! stupidest ! org
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> How can I refuse mail from hosts who don't have an open port 25?
>
> What do you think from such a check?

i have tried this, it's not useful, so i didn't leave the check in
place

it's very common, perhaps even the norm that the IP address which
delivers mail to me itself will not accept an incoming port 25
connection

> I've investigated why somebody did not receive mail from a virtual
> machine, and I found out her provider (reviced.nl) refuses all mail
> from a host what does not have port 25 open. I have much problems
> with spam and I would like to reduce it.

this will stop a lot of legitimate mail

and probably not stop much spam
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