PMDF's optional logging of message traffic is enabled via the logging channel keyword, as described in Section 2.3.4.85. Enabling logging causes PMDF to write an entry to a mail.log* file each time a message passes through a PMDF channel. Such log entries can be useful if you want to get statistics on how many messages are passing through PMDF (or through particular channels), or when investigating other questions such as whether and when a message was sent or delivered.

If you are only interested in gathering statistics on the number of messages passing through a few particular PMDF channels, then you may want to enable the logging channel keyword on just those PMDF channels of main interest. But more generally, many sites prefer to enable logging on all PMDF channels; in particular, if you are trying to track down problems, the first step in diagnosing some problems is to notice that messages are not going to the channel you expected or intended, and having logging enabled for all channels can help you spot such issues. See Section 2.3.4.85 for details on enabling logging.

In addition to the basic information always provided when logging is enabled, additional, optional information fields may also be logged in the mail.log files, controlled via various LOG_* PMDF options; see Section 7.3.6. Particularly likely to be of interest are the LOG_MESSAGE_ID, LOG_FILENAME, LOG_CONNECTION, and LOG_PROCESS options. Enabling LOG_MESSAGE_ID allows correlation of which entries relate to which message. Enabling LOG_FILENAME makes it easier to immediately spot how many times delivery of a particular message file has been retried, and can be useful in understanding when PMDF does or does not split a message to multiple recipients into separate message file copies on disk. Enabling LOG_CONNECTION causes PMDF to log TCP/IP connections, as well as message traffic, to the mail.log files by default; alternatively, the SEPARATE_CONNECTION_LOG option may be used to specify that connection log entries instead be written to connection.log files. When using LOG_CONNECTION to cause generation of TCP/IP connection entries, additionally enabling LOG_PROCESS allows correlation of which connection entries correspond to which message entries.

On UNIX and NT, mail.log and connection.log entries may optionally be duplicated to syslog (UNIX) or to the event log (NT) via the LOG_MESSAGES_SYSLOG and LOG_CONNECTIONS_SYSLOG options.

The exact information of interest in the mail.log files tends to vary substantially from site to site. Pointers to site written freeware utilities for analyzing the PMDF log files, which you may find a useful starting point, can be found at the Process Software web site:

http://www.process.com