If you are receiving bounce messages which are addressed to non existent users, you probably have a catchall setup on your domain.
Catchall is a way for the mail server to route emails which are addressed to invalid accounts at your domain. To prevent this, we recommend you disable your catchall. To disable your catchall, simply follow these steps:
1) Login to your cpanel account
2) Click on the mail settings
3) Click on default address
4) For each domain, there will be a box with the value of the default address for this domain. Enter ":fail: No such user here" in the box
That's all! That will help prevent your account from accepting emails addressed to non existent accounts.
