I just upgraded to 20.04 with v64 from v57 where we had archive@domain.com setup as an all email catcher, very important for our team.
Now it does not work and I cannot find any topic on this issue and have no clue on how to set it up…
Solved:
Just add to the bottom, a new line with always_bcc=archive@yourdomain.com in /etc/postfix/main.cf and restart postfix server (sudo postfix stop && sudo postfix start).
It really seems to be working. More about always_bcc here