On Thu, Dec 10, 2020 at 05:33:46AM -0800, Jon Leech wrote:
> The only meaningful messages in the mail logs were
>
> Dec 10 00:01:58 celly postfix/smtp[21050]: warning: relayhost configuration
> problem
> Dec 10 00:01:58 celly postfix/smtp[21050]: send attr reason = unable to look
> up host mail.sonic.net: Name or service not known
Is the "smtp" transport using "chroot" in master.cf?
> I can nslookup, dig (either A or MX records), telnet to port
> 587, etc. on mail.sonic.net, so it's not a general system DNS issue.
Are your tests performed as "root" or as an unprivileged user?
> The postfix FAQ sort of touches on this scenario in FAQs 52 and 53,
> but about all I can make of that is that it might be running in a chroot
> without the right resolv.conf or other resource to do a name lookup. If
> that's true, any ideas on how I can figure out where the chroot is?
The chroot is always the Postfix queue directory, typically
/var/spool/postfix. And its use is specified in the "chroot" column of
the master.cf service definition.
> And why this behavior would have suddenly started happening, without
> any changes in my local configuration (that I initiated, at least, and
> I don't have any auto-updates configured)?
A Debian update?
> I also have a query in to Sonic as to whether anything might have
> changed on their end - they are Linux-friendly, and even the front-line
> support people tend to be clueful.
Upstream is unlikely to be at issue. Not DNSSEC-signed, but no issues
otherwise:
https://dnsviz.net/d/mail.sonic.net/dnssec/
Best to not nag them with local issues on your end.
--
Viktor.
