MX Entry

http://www.webhostgear.com/272.html

The MX record, short for mail exchange record, an MX Record is an entry in a domain name database that identifies the mail server that is responsible for handling e-mail for that domain name. Basically you can have one server handle your website and another handle your email, such as Cpanel for the site and a Windows Exchange machine for mail if you want. You can also have multiple MX records so mail can go to more than one server and order them in priority by number, the lowest number will receive mail first but more on that later.

Is there a way to setup two email providers to receive email for the same domain to protect against the failure of one?

You would have multiple MX records setup for the domain pointing to
different hosts. If one was unavailable, multiple others could be
contacted.

This is done in the primary DNS record for your domain. Each MX record
has a numerical priority associated with it, with lower numbers
representing higher-priority mail servers. For example:

MX 10 primary.your-domain.tld
MX 20 secondary.your-domain.tld
MX 50 other.friendly-domain.tld

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&77

$TTL 14400
@ 14440 IN SOA ns1.domainname.com. info.domainname.com. (
2006020205
14400
7200
3600000
86400
)

domainname.com. 14400 IN NS ns1.domainname.com.
domainname.com. 14400 IN NS ns2.domainname.com.

domainname.com. 14400 IN A ip

localhost.domainname.com. 14400 IN A 127.0.0.1

domainname.com. 14400 IN MX 0 mail.domainname.com.

mail 14400 IN A ip1
www 14400 IN CNAME domainname.com.
ftp 14400 IN CNAME domainname.com.

$TTL 14400
@ 14440 IN SOA ns1.domainname.com. info.domainname.com. (
2006020205
14400
7200
3600000
86400
)

domainname.com. 14400 IN NS ns1.domainname.com.
domainname.com. 14400 IN NS ns2.domainname.com.

domainname.com. 14400 IN A ip

localhost.domainname.com. 14400 IN A 127.0.0.1

domainname.com. 14400 IN MX 0 mail.domainname.com.
domainname.com. 14400 IN MX 10 mai.google.com.
domainname.com. 14400 IN MX 20 mail.test.com.

mail 14400 IN A ip1
www 14400 IN CNAME domainname.com.
ftp 14400 IN CNAME domainname.com.

for checking

dig mx domainname.com