Thanks, idw. I'll just add here for completeness, that this option, whether set manually or by command line parameter, is a global setting; it applies to all your identities. 

I have just recently started using Pegasus 4.72.572. (It is running on Windows 7). In the "Internet Mail Options" dialog (accessed via "Internet Options..." in the Tools menu), there is a checkbox labelled "Create Internet Session Logs". If you tick that option, that setting is not retained between sessions. (Same behaviour in previous versions.) Is there any way (e.g. an INI file entry) to make that setting permanent? (I believe that in version 4.72, the logs created by that option appear in a subfolder named TCPLogs of the user's "home" mailbox folder. They are NOT the same as the logging referred to below.)

Also, previous versions of Pegasus, regardless of the setting mentioned above, kept a file named Syslog.pm in the user's "home" mailbox folder, in which it logged every piece of outgoing mail. It recorded the date, recipient, subject, identity in use, and the six message settings set by checkboxes in the message editor. Does version 4.72 keep such a log or can it be told to do so? And if so, what is the filename and where is it kept? 

Whoops - I found the answer to part two of the question, the option to switch on logging for outgoing mail is in the preferences (Tools > Options) - the second last item.

As for making the option to create internet (TCP) session logs permanent, I guess there is no way, but if anyone knows of one, please correct me.

[quote user="Moongazer"]As for making the option to create internet (TCP) session logs permanent, I guess there is no way, but if anyone knows of one, please correct me.[/quote]

Quote from PM's Help:

Create Internet session logs (advanced diagnostic use only)  Checking this control tells Pegasus Mail to create special log files that show the entire exchange of information between it and the servers it connects to. Each session will be created in a file called TCPxxxx.WPM in your home mailbox directory (the "xxxx" is replaced by four digits). Creating session logs will slow down the performance of your system somewhat, and you should be aware that any username and password information exchanged between Pegasus Mail and the server will be shown in the log, *even* if you use SSL to secure the connection. Session logs are primarily useful if you need to debug a problem between Pegasus Mail and one of the servers it connects to - you should enable the option only on instructions from a system administrator or from Pegasus Mail technical support. [ Technical note: this control has thesame effect as using a "-Z 32" commandline switch when you run Pegasus Mail ]

 One correction, though: In recent versions these log files are written to the ...\TCPLogs\ subdirectory of your home mailbox directory.