Is there any way to send email without logging to mail log


I’m having a server with a few other users on it (users don’t have ssh access).

I installed virtualmin to ubuntu server, everything set as default.

From what i see, every email sent out from my server will go through postfix, is it correct?

Also, is there any way to send out emails from the server without logging into the /var/log/mail.log file?

My story is: Recently my server was suspended by ISP for spamming reason. They say the server is sending out too fast (too many SMTP connections)

However, i told them that my mail.log showed that i only send out one email every “many minutes/hours”. And i showed them the log.

They say they are not sure, but it would be possible that i’m not only using postfix, and may be my users may be using other way to send out email without writing into the log.

So, i’m looking for the right answer to my problem. If there is such a secret and magical way to send out email, it would be great to know the details, so that i can have appropriate measure to fight against the spam method.

Thanks for any sharing!