Sending email without mail()

I have a site hosted at byethost. They says sendmail supported. The mail() function returns true. But the mail is not received.
So I used the phpmailer to use gmail SMTP. It is working. In the received mail my gmail id is shown. I changed the AddReplyTo and SetFrom in Phpmailer. But it is displayed as if I send it from my gmail account.

This hosting service has a webmail service pop3.
How to use that service in php to send mail so that [email protected] is displayed in the received mail?
Please help. Thanks in advance.