<domain *> max-msg-per-connection 20 max-rcpts-per-message 100 </domain> Use multiple virtual MTAs with increasing limits:
<acct-file /var/log/pmta/acct.csv> record job,vmta,domain,bytes,msgs,rcpts,status,dsn-status,time roll daily compress yes </acct-file> Monitoring via pmta command:
<domain gmail.com> max-smtp-out 20 max-msg-rate 200/h max-msg-per-connection 5 use-starttls yes dns-timeout 30 smtp-timeout 60 retry-after 300 final-retry-after 86400 </domain> <domain yahoo.com> max-smtp-out 15 max-msg-rate 150/h max-msg-per-connection 3 </domain>