Re: [exim] Mailma3 integrations

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Συντάκτης: Slavko
Ημερομηνία:  
Προς: exim-users
Αντικείμενο: Re: [exim] Mailma3 integrations
Hi,

Dňa 31. októbra 2021 18:31:59 UTC používateľ Sherin A via Exim-users <exim-users@???> napísal:
>It looks like you are not familiar with internet severs. I really don't
>want to setup a local or intranet resolver and revese dns lookup server
>for localhost.


The best practice for MTA is to have own recursive (and caching) DNS server, especially
(but not limited to) when you use DNS RBL lists. And when you use own DNS server, you
should be aware of RFC 1912, which says in 4.1 section:

    Certain zones should always be present in nameserver configurations (beside other):


    localhost
    0.0.127.in-addr.arpa


    ...


    The "localhost" address is a "special" address which always refers to the local host. It
    should contain the following line:


    localhost. IN A 127.0.0.1


    ...and relevant PTR for it.


(note the dot after localhost)

RFC doesn't tell MUST, only SHOULD, thus one do not need to have it, but having it prevents
its leak to upstream servers. And, when you do not have it, you cannot expect, that it will be
resolved by DNS query, what was clearly shown in your log line.

>root@u: ~ # dig localhost @8.8.8.8 +short
>root@u: ~ # nslookup localhost
>Server:        8.8.8.8
>Address:    8.8.8.8#53


Do not use google as ethalon, it is machine to make money, nothing less, nothing more...
Slavko