Setting Up DNS for Multiple Mail Hosts

If you want to set up a virtual host with an IP address, make the following entries in your DNS:

Add an MX record for the mail domain (for example, mail.domain2.com). The MX record identifies the host name of the virtual host.
Add an A record for the host name of the virtual host. The A record maps a host name to an IP address.
Add a PTR record for the IP address of the virtual host. The PTR record maps an IP address to the host name and is used for reverse lookups.

Example: The DNS entries for a virtual host with a host name of mail.domain2.com would look like:

SOA

$ORIGIN

...

domain2.com

10.50.21.156.in-addr.arpa.,type = PTR

host = mail.domain.com (PTR record)

A DNS lookup for mail sent to user@domain2.com would find that the mail must be sent to the host mail.domain2.com.

If you want to set up a virtual host without an IP address, make only one entry in your DNS: an MX record for the mail domain (for example, mail.domain3.com). This MX record identifies the host name of the primary mail host.

Example: The DNS entries for a virtual host without an IP address for which the host name is mail.domain3.com would look like:

SOA

$ORIGIN

...

domain3.com

A DNS lookup for mail sent to user@domain3.com would find that the mail needs to be sent to the host mail.domain.com.

Note: The MX record for a virtual host without an IP address does not have to use the primary mail host domain name; the MX record can also use domain names of other available hosts with an IP address.

For more information about setting up the DNS entries, see:

A primer with examples in "How a Mail Server Uses DNS".
DNS Help on the IMail Support Center at:
http://www.ipswitch.com/Support/IMail/dns.html
Our Knowledge Base for IMail Support Center at:
http://www.imailserver.com/support/kb.html.

Note: You can use Ipswitch WS_Ping ProPack to look up DNS information. For more information about looking up DNS information using WS_Ping ProPack, see "Step 1: Confirm your DNS Settings" on page 23.