Oracle Linux - Postfix - showq: bad command startup

APPLIES TO:

Oracle Linux 7 to Oracle Linux 9
Linux x86_64 on Oracle Public cloud

SYMPTOMS:

The command mailq hangs and no output is sent STDOUT.

$sudo systemctl status postfix
* postfix.service - Postfix Mail Transport Agent    

Loaded: loaded (/usr/lib/systemd/system/postfix.service; disabled; vendor preset: disabled)    

Active: active (running) since <date and time>; 14h ago   

Process: 31182 ExecStart=/usr/sbin/postfix start (code=exited, status=0/SUCCESS)   

Process: 31179 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)   

Process: 31175 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=0/SUCCESS)  Main PID: 31281 (master)     

Tasks: 3    Memory: 5.8M    

CGroup: /system.slice/postfix.service        

    |-  845 pickup -l -t unix -u            |-33281 /usr/libexec/postfix/master -w            `-32283 qmgr -l -t unix -u
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