On Mon, Aug 05, 2024 at 09:00:48PM -0400, Joey J via Postfix-users wrote:
> I'm getting rejections showing:
> reject: RCPT from unknown[96.92.246.116]: 450 4.7.25 Client host rejected:
> cannot find your hostname
https://www.postfix.org/DEBUG_README.html#mail
- "postconf -nf" output (with verbatim whitespace/line breaks)
- "postconf -Mf" output (with verbatim whitespace/line breaks)
> But if I do an nslookup on the same box, it does resolve.
> I thought this was purely if no reverse exists reject.
Things could be different when DNS queries are issued from inside the
chroot jail (Debian/Ubuntu enable chroot for most Postfix services by
default) or when executed by the postfix user, rather than say root.
The lookup failure may also have been transient (as evidenced by the
"450" response code, though, after initial burn-in, you may not have
known to set:
plaintext_reject_code = 550
unknown_address_reject_code = 550
unknown_client_reject_code = 550
unknown_hostname_reject_code = 550
unverified_recipient_reject_code = 550
unverified_sender_reject_code = 550
The (initial safety net) defaults are:
plaintext_reject_code = 450
unknown_address_reject_code = 450
unknown_client_reject_code = 450
unknown_hostname_reject_code = 450
unverified_recipient_reject_code = 450
unverified_sender_reject_code = 450
These should be changed once you believe your configuration to be sound.
--
Viktor.
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