PMDF System Manager's Guide

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.

The keywords multiple , addrsperfile , single , and 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. multiple , 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.

The 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.)