global host_name = mail.example.com; domain = example.com; log_level = 3; pid_file = /var/run/powermta.pid;
ISPs will rate-limit or block your IPs if you open too many connections or send too many emails per hour. You must configure custom rules for each major provider.
# Check queue pmta show queue --domain gmail.com
Example:
max-msg-rate 1000/second # Global sending throttle max-errors-per-domain 10 # Soft bounce limit before backoff max-errors-per-ip 5 # Per-IP error limit