tmda-pending -bS weirdness

This snippet is from qbrowse.tk:

        # We have to go through some contortions here, because
        # tmda-pending outputs a summary at the end which doesn't
        # normally show up at the console. Must investigate further.
        #
        # There's also probably a better way to find out where the
        # summary starts, but for now we have to split and rejoin the
        # message after finding the message ID.
        set RawMsg [exec tmda-pending -bS $FileName]
        foreach line [split $RawMsg \n] {
            if ![string match $FileName* $line] {
                lappend MessageText $line
            } else {
                break
            }
        }
        unset RawMsg
        set MessageText [join $MessageText \n]

I've tried several different ways of reading the data, and am completely
confused as to why the summary shows up at the end of the data stream.
This happens when I exec tmda-pending, as well as when I read the output
from a pipeline.

Anyway, the functional question is this: should tmda-pending displaying the
summary at all? What file descriptor is it sending it on? And why can't
I make it stop? :)

-- 
Unabashedly littering the information superhighway with detritus like
this for over 15 years now.