Checking Configuration of the Primary Host

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After installing IMail Server, you should have a single mail host configured (the primary mail host). Check the following items in the primary mail host configuration:

• This primary mail host often has the same name as the host on which you installed IMail Server. This is the official host name that you see when you expand the localhost folder in the left panel.

If you do not want to use the official host name of your server as the name of the primary mail host, you can create an alias for the primary mail host. See "Setting Up an Alias for a Host" for information.

• The DNS server for the local network must appear on the IMail Administrator SMTP tab. Click the SMTP tab to check the DNS server setting, the DNS server's IP address should display in the Domain Name Server address box.

Note: You can see your own DNS records (and those of any host) with the Lookup utility in Ipswitch's WS_Ping ProPack, a network information tool. An evaluation version of WS_Ping ProPack is included on the ICS Server CD or is available on the Ipswitch Web site: www.ipswitch.com.

Checking the DNS Configuration for the Primary Host

For background information about DNS records, see "Appendix A: Mail Servers and the DNS" in the IMail Server Getting Started Guide.

Setting Up DNS for the Primary Host

Verify or create the following entries for your primary mail host in your DNS:

• An MX record for the mail domain (for example, domain.com). The MX record identifies the host name of the computer running the mail server (the IMail Server computer).
• An A record for the host name of the computer running IMail Server. The A record maps a host name to an IP address.
• A PTR record for the IP address of the computer running IMail Server. The PTR record maps an IP address to the host name and is used for reverse lookups.

Example: The DNS entries for a host with an official host name of mail.domain.com would look like:

SOA 
$ORIGIN 
... 
domain.com 
     IN MX 10 mail.domain.com		(MX record) 
     mail IN A 156.21.50.5		(A record) 

5.50.21.156.in-addr.arpa.,type = PTR
host = mail.domain.com (PTR record)

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

Setting Up DNS for Multiple Mail Hosts

For a virtual host with an IP address, you must make the following entries in your DNS:

• An MX record for the mail domain (i.e. mail.domain2.com). The MX record identifies the host name of the virtual host.
• An A record for the host name of the virtual host. The A record maps a host name to an IP address.
• 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 
     IN MX 10 mail.domain2.com		(MX record) 
     mail IN A 156.21.50.10		(A record)  

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.

For a virtual host without an IP address, you must make only one entry in your DNS: an MX record for the mail domain (i.e. mail.domain3.com). This MX record identifies the host name of the primary mail host. As an 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 
     IN MX 10 mail.domain.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.

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