Question about E=mail and OSCommerce

[Legerdemain]

greetings,

 

I have had this slightly annoying problem since I installed OSCommerce (via Fantastico).

When I try to send out e-mails it comes back as Undeliverable, Routing issue.

 

I have changed my e-mail address to send from to <username>@localhost.

 

THis works fine, however, if I switch it to <username>@domain.com, it bounce back.

 

Is this an OSCommerce issue, or Server issue.

 

If server issue, what would be the likely cause.

 

INFO: Currently hosting via someone else, would need to relay information to them to try to fix this.

 

Thanks as always,

Jeff