"Undelivered Mail Returned to Sender" on daily execution of popularity-contest submission

Support
,
1

What type of hardware are you using: Old laptop or computer
What YunoHost version are you running: 12.0.14
How are you able to access your server: The webadmin
SSH
Direct access via physical keyboard/screen
Are you in a special context or did you perform specific tweaking on your YunoHost instance ?: Yes: Using a separate server to bypass NAT using Wireguard

Describe your issue

The package popularity-contest (or popcon for short) is a package that sends Debian a list of the installed packages daily in order to check for package popularity, hence the name. However, for some reason, my email backend seems to be unable to actually send the email, returning an error message instead (see below).

Share relevant logs or error messages

The header of the email I get sent every day:

This is the mail system at host azkware.net.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<MAILER-DAEMON@azkware.net>: user unknown


Reporting-MTA: dns; azkware.net
X-Postfix-Queue-ID: 3A92568C509D
X-Postfix-Sender: rfc822; root@azkware.net
Arrival-Date: Mon, 14 Apr 2025 23:25:05 -0600 (CST)

Final-Recipient: rfc822; MAILER-DAEMON@azkware.net
Original-Recipient: rfc822;MAILER-DAEMON@azkware.net
Action: failed
Status: 5.1.1
Diagnostic-Code: x-unix; user unknown
2

But

Anyway, try changing the sender email like proposed here https://popcon.debian.org/FAQ


A) To send as user 'myuser', edit the function 'do_sendmail' in
/etc/cron.daily/popularity-contest to

  do_sendmail()
  {
    su myuser -s /bin/sh -c "/usr/sbin/sendmail -oi \"$MAILTO\""
  }
3

OK, I found that the do_sendmail function has changed a bit during the meanwhile:

do_sendmail()
{
        if [ -n "${MAILFROM}" ]; then
                sendmail -oi "${MTAOPS}" -f "${MAILFROM}" "${MAILTO}"
        else
                sendmail -oi "${MTAOPS}" "${MAILTO}"
        fi
}

I suppose the su myuser part goes on the else half of the if, right? And also, which user do I use for myuser here? (I don’t remember having an admin account anymore, and root should work by default - what’s happening here?)

4

Your username. Root, admin and admins @domain are aliases