Trigger when user logs in

Hi,

PCI auditors have mandated that our databases (all running v9.6) send an
email when certain users log in.  Thus, I've been searching for how to do
this, but without much luck.

https://www.postgresql.org/message-id/flat/20170720204733.40f2b7eb.nagata%40sraoss.co.jp

This long thread from almost two years ago seems to point in the right
direction, but then died with "Okay, this has proved to require broader
changes than thought first. I am marking the patch as returned with feedback."

So, is there something that I've missed which lets me write an "on login"
trigger, or do I have to install pgaudit and tail_n_mail?

Thanks

--
Angular momentum makes the world go 'round.