I have site owner set to my email address,
grep 01623500076 /var/log/mail.log
2026-02-01T11:00:10.006412-05:00 dap002 postfix/pickup[113387]: 01623500076: uid=1001 from=<mailman> 2026-02-01T11:00:10.017044-05:00 dap002 postfix/cleanup[113728]: 01623500076: message-id=<20260201160010.01623500076@dap002.localdomain> 2026-02-01T11:00:10.055506-05:00 dap002 postfix/qmgr[66308]: 01623500076: from=<mailman@dap002.localdomain>, size=6012, nrcpt=1 (queue active) 2026-02-01T11:00:10.106626-05:00 dap002 postfix/local[113730]: 01623500076: to=<mailman@dap002.localdomain>, orig_to=<mailman>, relay=local, delay=0.16, de lays=0.11/0.01/0/0.04, dsn=5.2.0, status=bounced (cannot update mailbox /var/mail/mailman for user mailman. cannot open file: Permission denied) 2026-02-01T11:00:10.140212-05:00 dap002 postfix/bounce[113731]: 01623500076: sender non-delivery notification: 19ED7500078 2026-02-01T11:00:10.182157-05:00 dap002 postfix/bounce[113731]: 01623500076: postmaster non-delivery notification: 227BC50007D 2026-02-01T11:00:10.183279-05:00 dap002 postfix/qmgr[66308]: 01623500076: removed
I assume you meant sudo chown mailman /var/mail/mailman.