Host4Profit email spam

If they're sending mail using your email address, but they're not sending it through Host4Profit, then they're just pretending to be you. There's no technical solution available to solve that problem. I used to receive thousands of bounce emails a day as a result of spoofing.

If they've actually hacked into your account or are somehow using a security weakness on your website to send emails as you from the Host4Profit servers, then you need to audit your applications (check for updates, inspect outbound mail audit trails, check http access logs) and your hosting account (login times and source ip addresses, secure passwords, ssh keys).

You can tell the difference between these two cases by comparing the full headers of a legitimate email sent from your hosting account to the full headers of a spam email sent by the spammer. Focus on the Received headers - they're ordered from newest (top) to oldest (bottom) in the email. If you need further help, consider pasting one set of Received headers from a legit message, and one set from a spam message, here for inspection.