Hi Nikolas,
You have two options:
- Clear all SMTP values in Moodle. This will make the mailer library use the `sendmail` binary if it is in the path (it normally is). This is typically the fastest option as it uses sockets rather than ports.
- Use the SMTP option if you have configured it - i.e. localhost on port 25. This will still be fast but will open a port for each mail sent. This has an inherent TCP overhead and time cost, but it's negligible.
Best wishes,
Andrew