PMDF allows multiple destination addresses to appear in each queued message. Some channel programs, however, may only be able to process messages with one recipient, or with a limited number of recipients, or with a single destination system per message copy. For example, the SMTP client programs for the TCP/IP channels only establish a connection to a single remote host in a given transaction, so only addresses to that host can be processed (this despite the fact that a single channel is typically used for all TCP/IP traffic). Another example is that some SMTP servers may impose a limit on the number of recipients they can handle at one time, and they may not handle errors in this area at all gracefully; similar concerns may also arise on the local channel when MAIL-11 connections are being used.
single_sys can be used to control
how PMDF handles multiple addresses.
single means that a
separate copy of the message should be created for each destination
address on the channel.
single_sys creates a single copy
of the message for each destination system used.
the default, creates a single copy of the message for the entire
channel. Note that at least one copy of each message is created for
each channel the message is queued to, regardless of the keywords used.
addrsperfile keyword is used to put a limit on the
maximum number of recipients that can be associated with a single
message file in a PMDF channel queue, thus limiting the number of
recipients that will be processed in a single operation. This keyword
requires a single integer argument specifying the maximum number of
recipient addresses allowed in a message file; if this number is
reached PMDF will automatically create additional message files to
accomodate them. (The default
multiple keyword corresponds
to imposing no limit on the number of recipients in a message file.)