MX Record

MX Record (Mail Exchange Record)

A mail exchanger record (MX record) is a type of resource record in the Domain Name System that specifies a mail server responsible for accepting email messages on behalf of a recipient's domain, and a preference value used to prioritize mail delivery if multiple mail servers are available.

MX is an acronym for Mail exchange. It specifies the name and relative preference of mail servers for the zone. MX is a DNS record used to define the host willing to accept mail for a given domain. I.e. an MX record indicates which computer is responsible for handling the mail for a particular domain.

Without MX Records for your domain, only internal e-mail will be delivered to your users.

E-mail from other mail servers will not be able to reach your server simply because these others servers cannot tell to which server they need to open a connection or Delivery.

Each MX record requires a preference value that tells mailers sending mail the order in which to contact the destination's mail servers. The lower the preference value, the more preferred the mail server. The value 0 is most preferred, 65535 is least preferred.

You can have multiple MX records for a single domain name, ranked in preference order.

MX Records must be in the following format:

domain.com. IN MX 10 mail.domain.com.

Query For MX Record with Help NSLOOKUP

   Open a Command Prompt (Start, Run, cmd, [Enter])

Type nslookup.

Server (The DNS server that you want to use. This is optional.)
Set q=mx (This sets the query type to "MX" {Mail Exchanger}.)
(The domain name you want to lookup the mail exchanger to.)

This operation can be done on Windows XP, Windows Server 2003, and Windows Vista. There are similar options if you are doing this from Linux.