Getting error 550 from bounced email to my email

Hi all. I have a server setup running Virtualmin, and i created a mail account on the box. I can send email from the server, but I cannot recieve mail to the box.

IF I send an email to the account, I keep getting a error 550. Example, if I send a email from my gmail account to the email on my server, it bounces back with a 550.
Any suggestions as to what I should check?

Whenever you send an email to your box, do you see any errors generated in the email logs? (/var/log/maillog or /var/log/mail.log)