Is it possible to change the MX records of a subdomain, so that mail sent to:

subdomain.domain.com

is sent to mail.oneplace.com

and mail that is sent to:

domain.com

is sent to mail.anotherplace.com ?

Thanks

Sure, that can be done, but if you don't have control over your DNS, then you'll have to contact your host to make the change for you.

I have control of DNS on the server (System Administrator), I just don't know what changes to make to the DNS Zone file. I have tried it in the past, but I never could get it to work? Could you tell me what I need to add to the file or what it should look like?

Thanks

Just modify the existing MX record or add a new MX record as appropriate for the domain and subdomain and enter the appropriate mail server as the mail exchanger. Make sure the mail servers are setup to handle mail for the appropriate domain or subdomain.

Example:

domain.com. MX 10 mail.anotherplace.com.
subdomain.domain.com. MX 10 mail.oneplace.com.