After updating to version 71, I get the message "status bounced unknown user"

Help with Setup/Upgrade
1

Hello,

After updating to version 71, I have the following message in my mail log:

postfix/local[129671]: 27EEE202D90: to=user1@dom.int, relay=local, delay=0.11, delays=0.09/0.01/0/0.01, dsn=5.1.1, status=bounced (unknown user: “user1”)

Does anyone have any ideas?

Thank you for your help.