Variation for Debian 10 + Dovecot 2.3.4.1:
cat /var/log/dovecot/dovecot.log | grep imap-login:\ Info:\ Login | sed -e 's/.*Login: user=<\(.*\)>, m
ethod=.*/\1/g' | sort | uniq | wc -l
Variation for Debian 10 + Dovecot 2.3.4.1:
cat /var/log/dovecot/dovecot.log | grep imap-login:\ Info:\ Login | sed -e 's/.*Login: user=<\(.*\)>, m
ethod=.*/\1/g' | sort | uniq | wc -l