Must I Use My ISP SMTP Mail Server?

Hello,

I am trying to configure POP3 email addresses in Outlook. For incoming POP3 I can use my domain mail server, which works fine. However, my hosting service has informed me that I MUST use my ISP outgoing SMTP mail server.

Is there any way around this? My ISP mail server will not allow me to send mail to several different web based mail services like mail.com and hotmail.

I want to be able to specify my domain mail server for both incoming and outgoing and don’t understand why I can’t do this. Is this unique to my hosting service, or is it a rule among them all?