Wrong guesswork above re M & T lines. Further experimentation suggests that the M line is generated when the Message is queued for delivery (if that's what you've configured the SMTP definition to do), and the T line is generated when you send the queued mail.

Syslog.pm (Pegasus's log of outgoing mail) has no column headers at the top. Anyone know what the (non obvious) info in some of the columns signifies? (In particular, col 2, and the two columns after the subject.) (Asked before here, but not much info provided.)

The following is my theory (pure guesswork) as to why, for each piece of outgoing mail, this log has two lines that are almost identical, but with "M" and "T", respectively, in column 2: From the date column, you can see that the two entries are usually less than 1 minute apart, but sometimes more.

So this may have something to do with how the mailer transmits data to the SMTP server. Not sure exactly how this is split up into two lots, but it sends: sender info, recipient(s) info, other header stuff and the message body. (Could M & T mean Message and Tansport info?) Comments anyone?