Managing mail with MMDF

Domain tables

MMDF uses domain tables to match a short host name to its fully qualified host name. This allows users to address mail to other machines within a host's domain using just the host's name, instead of requiring each host's fully qualified domain name in addresses. For example, if the domain your_company.COM includes machines named volga, yangtze, mekong, and seine, a user on volga can address mail to user andrei on yangtze as andrei@yangtze instead of having to use the fully qualified name, andrei@yangtze.your_company.COM.

Domain tables can also convey information to MMDF about how machines are connected, and they can specify special domain routing considerations.

Domain tables are named using domain_name.dom (except for root.dom, which contains any domain information not named in other domain tables). The standard practice is to maintain a separate domain table for the domain in which the host machine resides. Domain tables are created by default in the /usr/mmdf/table directory (or the directory specified by the MTBLDIR parameter in the mmdftailor file).

The SCO OpenServer system includes two domain tables in the /usr/mmdf/table directory:

Domain table Domain Describes
local.dom local machines in the local domain
root.dom root domains not listed in other domain tables

NOTE: The root.dom table also contains information about how to access top-level domains, such as MIL and GOV. (The name root implies the top level of a hierarchy.)

Use the Domain Administration Manager to create new domain tables for each domain. For example, create a domain table for the domain and name it your_company.dom. You do not need to use the *.dom naming scheme; however, this filename extension makes it easier to determine the purpose of the file.

Domain table format

Each domain table consists of at least two columns of information: the first (leftmost) column lists the host name and the second column lists the fully qualified name for that host. The domain names can be either upper- or lowercase. Use tabs, spaces, a colon, or a combination of these characters to separate the columns. Additional columns indicate names of one or more forwarding machines (machines through which mail should be routed for delivery to the host listed in the second column).

The name of a domain table determines the domain names for which MMDF searches. For instance, the domain table for UUCP generally contains entries for names in this form:

   hostname:	hostname.UUCP
However, you can create an entry to map a specific UUCP address to another address. For example, to map research.uucp to, the entry in the uucp.dom table looks like this:
The following sections give examples of different domain tables.

The local.dom table

The local.dom table describes the machines in the local domain (independent of the channel that MMDF uses to reach each machine). For example, if there are four machines in the domain, the domain.dom table looks like this:

   volga:		volga.your_company.COM
   yangtze:	yangtze.your_company.COM
   mekong:		mekong.your_company.COM
   seine:		seine.your_company.COM
The domain.dom table maps each machine to the fully qualified host name in the domain.

The root.dom table

The root.dom table defines any the hosts and domains not defined in the other domain tables. This table can also contain information about how to access top-level domains, such as MIL and GOV. For example, if your host connects to the UUnet network system, you can set up MMDF to send all mail addressed to specific domains to To do so, set up your root.dom table like this:

   COM:	uunet.UU.NET
   EDU:	ucscc.EDU
   MIL:	uunet.UU.NET
   GOV:	star.GOV
   NET:	uunet.UU.NET
In this example, all mail directed to the com, mil, and net domains is sent out on UUnet; mail directed to the gov domain goes to; and mail sent to the edu domain goes to This includes mail addressed to domains that are contained within the named domains. For example, mail sent to is sent to unless a separate domain entry exists for or for

The uucp.dom table

The uucp.dom table is created if UUCP is configured on your system and if you add any hosts with a fully qualified name of hostname.UUCP . This table describes the hosts in the UUCP domain. For example, if your host connects to the remote machines cactus or palm via UUCP, the uucp.dom table looks like this:

   cactus:	cactus.UUCP
   palm:	palm.UUCP
In this case, MMDF directs any mail sent to the cactus or palm machines to the UUCP network.

Creating other domain tables

Use the Domain Administration Manager to create new domain tables. When you subsequently add new hosts that belong to that domain, they are added to the appropriate table. For example, if you create the domain table rivers.dom and then add a host named nile.rivers.COM, this entry is added to rivers.dom:

   nile:	nile.rivers.COM

LAN considerations

If you are configuring MMDF for use on a local area network (LAN), you can use the domain tables to distribute the processing load on the machines, or you can designate a special mail server machine to route all the messages.

You have these choices:

Next topic: Channel tables
Previous topic: Modifying MMDF table parameters

© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003