On 10 Mar 2020, at 10:26, Catalin Bucur wrote:
Hello,
I have a question about how Postfix generate warning messages about
non-existent domains, non-existent MX domain names or for timeout
connecting to a destination mail server. In fact, my real problem is
that postfix does not warn me about nothing when I incorrectly write
the domain name for an email address AND by chance that domain exists
but does not have configured MX record on its DNS.
For example for a non-existent domain I receive almost instantly the
message /"t...@asdasdasd.ro <mailto:t...@asdasdasd.ro>: Host or domain
name not found. Name service error for name=asdasdasd.ro type=A: Host
not found"/
For an existing domain but without MX, I receive the error /"Host or
domain name not found. Name service error for name=onedomain.com
type=MX: Host not found, try again)"/, but AFTER
/maximal_queue_lifetime/, which is very annoying. In this case the
sender finds out only after 5 days about the real problem.
This should only happen in cases where the target domain has no MX
record but does have an A record, and the host at the A record's IP has
no mail service.
Fallback to A records is a standard part of how SMTP works. MX records
are not required for mail delivery and never have been.
Is there any way to modify postfix configuration to inform the sender
about such a problem instantly and to retry to send message until
/maximal_queue_lifetime/ expires?
Not instantly, but you CAN warn the user sooner by setting a short
non-zero delay_warning_time. It should probably be at least as long as a
slow DNS lookup might take.
From the postconf(5) man page:
delay_warning_time (default: 0h)
The time after which the sender receives a copy of the message of
mail
that is still queued. The confirm_delay_cleared parameter
controls
sender notification when the delay clears up.
To enable this feature, specify a non-zero time value (an
integral
value plus an optional one-letter suffix that specifies the time
unit).
Time units: s (seconds), m (minutes), h (hours), d (days), w
(weeks).
The default time unit is h (hours).
See also: delay_notice_recipient, notify_classes,
confirm_delay_cleared.
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not For Hire (currently)
