MMDF uses the channel tables to determine the channel to use for outgoing mail and the address of the host on that channel. Channel tables map the fully qualified host name (as determined from the domain table entries) to channel-specific addressing information. For example, the UUCP channel table maps host names to UUCP paths (using exclamation points) specifying how to get to each host. Channel tables are created by default in the /usr/mmdf/table directory (or the directory specified by the MTBLDIR parameter in the mmdftailor file.)
SCO OpenServer systems include two channel tables in /usr/mmdf/table:
The local.chn table contains entries describing all the names local host is called, mapping them to the local host name. For example, if the local host is volga.your_company.com, then the local host is known as volga on the local machine. The local.chn table maps the local host name (on the right) to the different ways people might refer to volga. This file looks like this:
volga: volga your_company.COM: volga volga.your_company.COM: volgaThis table should minimally include entries for the local host name and the full local domain (the values of the mmdftailor(F) MLNAME and MLDOMAIN parameters).
The list.chn table contains information about the list-processor program:
list-processor: list-processor list-proc: list-processorThese entries tell MMDF to pass mail addressed to a mailing list to the list-processor program. See ``Alias and mailing list tables'' for more information.
The uucp.chn table is created if UUCP is configured on your system and if you add any hosts that your host will connect to using the UUCP channel. The table describes how to route mail to those hosts. For example, the format of this file looks like:
mcvax.UUCP: uunet!mcvax!%s sri-nic.ARPA: uunet!sri-nic.arpa!%s uunet.uu.NET: uunet!%sThe left column contains the UUCP host name from the domain tables; the right column describes the UUCP address that MMDF uses to direct mail to that host. The ``%s'' at the end of the UUCP address means to use the rest of the address from this point on. In other words, when mail is addressed to the user hillis at mcvax.uucp, the UUCP channel passes the mail to UUnet along with the rest of the UUCP address (mcvax!hillis). The second entry in this example shows how a domain name (sri-nic.arpa) can be used within a UUCP path.
Channel table entries for the UUCP channel (in the uucp.chn file) when the destination machine is multiple hops away, appear like this:
stooges.UUCP: moe!curly!larry!stooges!%sSpecify the address of the host on the right hand side, where the address is a UUCP path.
For more information about configuring UUCP, see ``Connecting to other computers with UUCP''.
The smtp.chn table is created if TCP/IP is configured on your system and if you add any hosts that your host will connect to using the SMTP channel over TCP/IP. The table describes how to route mail to those hosts and includes their IP addresses. The format of this file looks like:
yangtze.your_company.COM: 192.0.0.1 mekong.your_company.COM: 192.0.0.2 seine.your_company.COM: 192.0.0.3The left column contains the fully qualified host names for the hosts that you connect to with TCP/IP and the right column contains the IP addresses. For more information about configuring MMDF to route mail over TCP/IP, see ``Administering TCP/IP''.