timeout when sending mail about orphaned users

[baszoetekouw]

We enabled the orphaned_users cronjob, which was suppossed to remove a few hundred (~350) users last Saturday.

The users seems to have bene removed, but the mail recording this was never sent:

Apr 01 03:02:50 sbs-pf1 postfix/smtpd[333879]: connect from localhost[127.0.0.1]
Apr 01 03:07:51 sbs-pf1 postfix/smtpd[333879]: timeout after EHLO from localhost[127.0.0.1]

Could it be that rendering the template https://github.com/SURFscz/SBS/blob/main/server/templates/orphan_user_delete.txt takes too much time?

In any case, this is rather annoying as we now have no record of which orphaned users where removed.

I propose the following changes:

• first render the templates, and only after that start the connection to the mail server.
• determine why rendering take so long. Maybe it helps if we only pass a list ofUser.uids to the templating engine, instead of a list of User objects? I can imagine those being rather bulky.
• Handle retrying mail sending if the first attempt fails. Maybe try up to five times, and if that fails dump the mail content to the logs.
• output the (uids of the) users who have been deleted to the log

[baszoetekouw]

Tested. Orphaning 400 users now takes 1300ms.