$ /usr/local/psa/admin/sbin/mailqueuemng --clean
Here is what the above code is Doing:
1. It’s using the find command to find all files in the /var/spool/postfix/maildrop directory that are older than 30 days.
2. It’s using the xargs command to execute the rm command on each of the files found in step 1.
3. It’s using the mailqueuemng command to clean the mail queue.