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List:       postfix-users
Subject:    Re: Refuse mail from hosts with closed port 25
From:       Paul van der Vlis <paul () vandervlis ! nl>
Date:       2019-09-16 13:17:00
Message-ID: 7a6e6d4f-d7b5-2a4f-bfea-eddbf08ba1cd () vandervlis ! nl
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Op 16-09-19 om 14:53 schreef John Peach:
> On 9/16/19 8:47 AM, Paul van der Vlis wrote:
>> Hello,
>>
>> How can I refuse mail from hosts who don't have an open port 25?
>>
>> What do you think from such a check?
> 
> 
> DO NOT DO THIS!
> 
> A significant number of installations will use different servers for
> inbound and outbound email.

I know a provider what is actually using this. I guess only the big
providers will have different servers for inbound and outbound email,
and you can make a list of them.

> What is worth checking, is that the sender has MX records.

Hmm, interesting idea!
Maybe you have some lines on how to configure this?

But, I am affraid many hosting providers will not have a MX record on
the hosting server, so you don't get your "forgotten password" from the CMS.

With regards,
Paul


-- 
Paul van der Vlis Linux systeembeheer Groningen
https://www.vandervlis.nl/
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