The list channel performs two basic services. First, it postpones the verification of the list addresses and performs the (possibly lengthy) verification in the background when the list channel resubmits the message to the mail system. This prevents tying up a network connection or a user's terminal when verifying a long mailing list. Second, the list channel will, under special circumstances, change the return address for the message to a generic maintainer's address. The return address is determined by first taking the destination address (for example, ``largelist'') and seeing if there is an address in the alias file called ``largelist-request''. If there is, then ``largelist-request'' is used as the return address. If that was not found, the list channel checks to see if the destination address has a trailing ``-outbound''. If so, this is stripped and a ``-request'' is added and the lookup in the alias file is made a second time. If the ``-request'' address is found, then that address is used as the return address. If no ``-request'' address is found, then the original return address is used (normally the address of the sender).
largelist: largelist-outbound@list-processor largelist-outbound: :include: /usr/mmdf/lists/largelist-file largelist-request: maintainerThe first line causes mail sent to ``largelist'' to be sent through the list processor, readdressed to ``largelist-outbound''. The second line is what actually references the mailing list file for ``largelist''. The third line is optional, and is used to set up the (informal) standard maintenance address. This -request address, if present, will also be used by the list channel as the return address for mail submitted to the list.
When you use the MMDF Administration manager's Alias Administration client to set up a mailing list, these entries are created for you. See ``Managing mail aliases and lists'' in Managing Mail with MMDF for more details.