Fortunately it does not happen often - or it might be only me with
little experience - yet it happened to me first time someone said:
...
said: 451 X-Warn: FCrDNS failed (in reply to RCPT TO command)
...
Are there any "tricks &| hacks" you know Postfix offer to remedy this?
many thanks, L.
On 18.11.25 12:54, Peter via Postfix-users wrote:
https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS
In summary: Your IP address should resolve to $myhostname (via a DNS
PTR record), which in turn should resolve back to your IP (A and/or
AAAA record).
Not necessarily the $myhostname, but it should:
- resolve the IP to hostname that resolves back to the IP
- the hostname should not be generic
(mail servers often refuse hostnames containing text "dynamic" or format
11-22-33-44.example.net)
Further the $smtp_helo_name (which defaults to $myshostname) should resolve
to an IP (not necessarily the outgoing IP but it's most logical).
On 18.11.25 10:17, lejeczek via Postfix-users wrote:
Certainly no PTR record for my IP but - do ISPes even do that - for us
at home or in general customers anywhere, as opposed to
co-located/hosted stuff? (or registrars who can, who do reverse too?)
I'm not going to move home there to such ISP's area, but sincere
question, just out of curiosity.
These are rules for mailservers that send outgoing mail to other
mailservers.
These aren't required for other hosts that send mail using
smarthosts/mailservers.
I read somewhere that 'hosts' locally, of such a private postfix might
play a role - when /hosts resolve/**to *localhost* (first or only) and
then postfix might send/use that - I don't remember details, if that
was a valid issue at all, but..
even then, is is only this time so for, in a couple years, when I got
FCrDNS, so should not be my postfix/setup.
This mostly depends on your host's usage, see above.
You can override public DNS by /etc/hosts only locally, and for outgoing
lookup when you set smtp_host_lookup or lmtp_host_lookup to "native".
--
Matus UHLAR - fantomas, [email protected] ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Quantum mechanics: The dreams stuff is made of.
_______________________________________________
Postfix-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]
