"Status Warning" - SSH continually restarting after port change

Hi guys,

Due to lots of (failed) brute force attempts over SSH, I've decided to change my SSH port to 30.

I opened up /etc/ssh/sshd_config and changed the port in there and restarted SSH and it works fine. However, when I did that, I started getting these e-mails titled "Status warning from my.hostname.com" every 5 minutes:

Obviously SSH is being restarted each time. I assume that it does not like my port change - why is this? How do I stop these e-mails from being sent?

Thanks