Main documentation is here: https://docs.mailcow.email/

cd /opt/mailcow-dockerized
./update.sh --stable

Source: https://docs.mailcow.email/i_u_m/i_u_m_update/

The commands below should work but for me it was more reliable to reboot the system.

cd /opt/mailcow-dockerized
docker-compose down
/etc/init.d/docker stop
iptables -F
/etc/init.d/docker start
docker-compose up -d

Source: https://github.com/mailcow/mailcow-dockerized/issues/2500

Just send a Mail from an account not on the server you wanna test and add the follwing line as a single line:

XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X

The Mail should be rejected then.

Source: https://www.com-magazin.de/tipps-tricks/profi-wissen/teste-spamfilter-2664201.html