Setting Up a Mail Gateway

Setting Up a Mail Gateway

You can set up IMail Server to function as a mail gateway for another mail server so that mail for the other server is sent and received through the IMail Server. Often, people set up a mail gateway because their mail server uses a dial-up connection and is not always connected to the Internet.

If you want IMail Server to be a gateway for another mail server, the other server must be running SMTP.

To set up IMail Server as a gateway for another mail server, check the following:

The mail domain (for example, domain2.com) for which IMail Server is a gateway does not appear in IMail Server.
User accounts for the mail domain are on the other server.
The MX record for the mail domain must point to the IMail Server host. Thus, mail addressed to that domain will come to the IMail Server host. (This MX record is in the DNS used by the other mail server.)
The IMail Server host must be able to resolve the domain name to the IP address of the other SMTP server. This is accomplished by making an entry for the domain name and IP in the HOSTS file on the IMail Server host (located at: %WINDIR%\system32\drivers\etc).

This works because IMail Server checks the hosts file and IP information before checking the DNS server. IMail Server queues the mail until it is delivered to the other server, or until the Retry Timer setting multiplied by the Number of Tries has elapsed.

If you are using any of the Relay Mail for options on the SMTP Security tab, and want to relay outgoing mail for another mail server, the address of the other server must be added by clicking Addresses, and entering the remote IP's into the table.

The following example shows how you can set up IMail Server to accept mail for a domain (domain2.com) and forward all mail for this domain to another SMTP server. Assume the following:
Other mail domain name:	domain2.com
Emails are addressed to:	user@otherdomain.com
 
Host name of other SMTP server:	my.otherdomain.com
IP address of other SMTP server:	156.21.50.240
 
Host name of IMail Server:	my.imailserver.com
IP address of IMail Server:	156.21.50.10 
The MX record for domain2.com would be mail.imailserver.com which would resolve to 156.21.50.10. To allow IMail to ignore the DNS records setup for domain2.com (which would cause IMail to deliver the message back to itself), create an entry in the local DNS file (a.k.a. HOSTS file). This file is located in %WINDIR%\system32\drivers\etc. In the HOSTS file, point the domain name to the IP address of the other SMTP server: 156.21.50.240 domain2.com.

Note: You can use the ETRN command to manually retrieve mail from the ISP's mail server. See "Using ETRN to Retrieve Mail" for more information.

Note: You can use the ETRN command to manually retrieve mail from the ISP's mail server. See "Using ETRN to Retrieve Mail" for more information.

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