mx record problem

[Rickead2000]

Hi,

I'm trying to set up a mailserver on a rented linux server I have.

However, I have done all that I thought i needed to do, but it doesnt work.

When sending an email to it, I get the following back from my ISP:-

test@mydomain.com
all relevant MX records point to non-existent host

A copy of the relevant parts of mydomain.hosts file is....

------------------

$ttl 38400
mydomain.com. IN NS ns1.registeredby.us.
mydomain.com. IN NS ns2.registeredby.us

www.mydomain.com. IN A 64.***.***.245
mydomain.com. IN A 64.***.***.245

mydomain.com. MX 10 mail.mydomain.com

---------------------

mail.mydomain.com
mydomain.com
www.mydomain.com

all resolve to the server.

Any ideas what is wrong? Or does the MX record need to be registered direct with internic?

Note: I can receive mails fine if sent using the server, ie the smtp server used is mail.mydomain.com