If you receive many emails that appear to have been sent by yourself, then you can help prevent spoofed emails by removing your own domain(s) from the Domain whitelist.

In the Administration module, go to "Configuration" > "Policies". Click the "Configure policy" button next to your policy. Then click the "Configure filter" button next to "SPAMfighter Sender Filter". Remove your own domain name from the Domain whitelist, and your own email address from the Email Address whitelist.

If you have questions or need help on doing this, SPAMfighter Support Department are always ready to help - just write an email to semsupport@spamfighter.com