Set email filtering from your cpanel.

You can set the mail filter from your cPanel.Please refer the following steps to set the filter.

1] Go to cPanel
2] Go to Mail >> email filtering
3] Click on Add filter option

This option is also very useful when your clients domain marked as Spam in your mail box.For example if mail came from example.com marked as Spam mail then you can set the filter in following manner to avoid Spam mail problem for your domain example.com

1] Go to cPanel
2] Go to Mail >> email filtering
3] Click on Add filter option
4] Then as per your email headers you can set the filter here
5] Destination should be allow
6] Click on activate option.

So that all the mails from example.com not be treated as spam.

Also refer following blog to collect more information http://theperfectarts.com/