Ever since I transfered over to a dedicated server, all mail coming from my domain name (ryankearney.com) is shown as coming from the server's hostname (zeus.ryankearney.com)

Also, all mail sent is ending up in my gmail spam folder. I suspect the aforementioned issue is the result in this.

Can anyone inform me as to why mail sent from my server is shown as coming from the servers hostname instead of the domain name the account is on?