Managing mail with MMDF

Searching MMDF domain tables

The submit(ADM) command uses the domain tables for two purposes: to specify the fully qualified host name and (optionally) to specify the route to a host by listing the fully qualified host names of one or more intermediate hosts through which mail is to be routed.

First, submit separates the fully qualified host name into two parts: the name of the domain table and the host name to match on the left-hand side of the entries in the domain table. For example, in the address david@engr.canada.com, the name of the domain table to search is canada.com and the host name to search for is engr.

MMDF tests an address for matches against the domain names in the MDMN entries in mmdftailor. For example, the address david@engr.canada.com matches this MDMN entry:

   MDMN   "canada.com", show="Canada Delivery", tbl=canadadom

Then, MMDF searches mmdftailor for the MTBL entry for canadadom:

   MTBL  canadadom,  file="canada.dom",   show "Canada Delivery"

MMDF uses the file associated with canadadom (canada.dom).

Thus, to route our message to david@engr.canada.com, submit uses this algorithm to search the domain tables for a match in the address:

Search for the host name (engr) in the left hand side of the canada.com domain table.
Search in the left hand side of the domain table (in this case, com), if it exists, for the domain name (engr.canada).
Search the left hand side of the root domain table for the fully qualified host name (eng.canada.com).
Search the relevant tables that include flags=route in the MTBL line in mmdftailor for substrings of the address. For example, search the com table for canada; search the root table for canada.com or com.
The flags=route parameter in the MTBL entry enables that table entry to match addresses for an entire subdomain, acting as a gateway. Do not use flags=route on tables other than the root domain table unless you have internal subdomains.
Search the tables that include flags=partial in the MTBL line in mmdftailor for the input name, in this case, the fully qualified host name (eng.canada.com), regardless of the domain name.
Use the flags=partial parameter on the local domain table so that users do not have to specify the full domain to send mail on the local machine.

If submit finds no match at all, as a last resort, it uses the badhosts channel, if it exists. Because MMDF uses the first domain that has an exact match without looking for other matches in later tables, the order in which you list MDMN definitions is significant. Make sure the local domain table appears first and the root domain table is last in mmdftailor.

If the address provided is username@host (for example, david@engr), MMDF performs the same search as described above except that there is no canada.com to match in the MDMN entries in mmdftailor. In this case, MMDF searches the root domain table and then the tables that include flags=partial in the MDMN line.