On 06.02.19 02:42, Patton, Matthew [Contractor] wrote:
I learned the hard way that if you don't set $myhostname to a FQDN you
can quickly end up on a black list despite having valid SPF records.
any evidence about this?
Returning to the OP's question, Postfix does append $mydomain to the
automatically derived value of $myhostname when the latter is not explicitly set
in main.cf and is not fully qualified.
Except that it doesn't. (or I misunderstood what you wrote)
I set $myhostname = 'smtp'.
$mydomain was also set.
I had to set both since gethostbyname() would have returned a value of
'ip-XXXXXX.aws.internal'.
what led you to the conclusion that your non-fqdn hostname caused RBL
listing?
I know servers that refuse non-FQDN helo.
I've seen servers that refuse invalid or generic DNS names
(ip-XXXXXX.aws.internal is both).
But I don't remember a RBL that would immediately list such hosts.
My HELO string was verifiably just $myhostname.
Precisely as documented: $smtp_helo_name defaults to $myhostname
http://www.postfix.org/postconf.5.html#smtp_helo_name
The naked 'smtp' was an
instant blacklist largely as a result of millions of vulnerable Microtek
home routers which have been exploited.
again, how do you know it got to any blacklist?
If Postfix had instead used $myhostname.$mydomain IFF $myhostname is not
FQDN (has no dots at all) then 'smtp'.$mydomain would have been perfectly
fine since there was an A record for it for quite some time.
well, since the $mydomain is by default taken from $myhostname, it should be
obvious you must set $myhostname to a FQDN.
Fair enough. But I still think that at the very least the docs should be a
little more explicit, and furthermore a warning is merited during
valid_hostname() and with SLOPPY_VALID_HOSTNAME we can continue without
error.
yes, apparently some of the docs could be little more explicit about
$hostname or $smtp_helo_name should be a FQDN.
--
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