==== Required information ====
- iRedMail version: 0.8.7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Ubuntu Server
- Related log if you're reporting an issue:
====

I can see that iRedMail does a good job of keeping hijackers out, but I'd rather have iRedMail quietly block these attempts. I'm talking about these:

This is the mail system at host (host).

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<greglee76@hotmail.com>: host mx3.hotmail.com[65.54.188.72] said: 550 Requested
    action not taken: mailbox unavailable (in reply to RCPT TO command)

These mean someone (a bot probably, because these happen in groups at the same time) tried to hijack my mail server to send spam, and couldn't because I assume relaying isn't allowed and they don't have the credentials to log in.

How can I make my mail server NOT let me know about these? It's kind of annoying because I have my phone set up to check my mail and I don't want to be bothered with this on my phone. K-9 mail can mark something as spam, but apparently does absolutely nothing about it, so I'd rather take care of this on the back end.