dovecot - Feb 2023 - Hide local IP from non delivery notifications

>> I have an external MTA configured with Postfix that delivers email to
an internal IMAP/LMTP
>> Dovecot server configured to bind an LDAP to check if users exist.
> 
> You should have postfix do the checking for whether or not users exist
> and then have postfix reject and deny the message.  Then you don't
> care because the IP of the postfix server is almost certainly your MX
server.

Plus backscatter. Sending a fail notification back to the sender (vs rejecting)
puts your mail server at risk of sending spam to email accounts that had their
address forged. And thus maybe yoru server being added to a spam blacklist.

Ok thanks for your answer but I have another question: if I reject the 
e-mail instead of sending the non delivery notification, how can a 
"good" user be notified of the fact that his e-mail was not delivered?

Claudio

On 14/02/23 19:48, dovecot at ptld.com wrote:
>>> I have an external MTA configured with Postfix that delivers email 
>>> to an internal IMAP/LMTP
>>> Dovecot server configured to bind an LDAP to check if users exist.
>>
>> You should have postfix do the checking for whether or not users exist
>> and then have postfix reject and deny the message.? Then you don't
>> care because the IP of the postfix server is almost certainly your MX 
>> server.
>
>
> Plus backscatter. Sending a fail notification back to the sender (vs 
> rejecting) puts your mail server at risk of sending spam to email 
> accounts that had their address forged. And thus maybe yoru server 
> being added to a spam blacklist.
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