http://www.jmaimon.com/qpopper/patches/qpopper-stats-read.v1.408.patch
set statistics-read = true
causes qpopper to log messages like this:
Stats: YYYYYYYY 1 3232 1 3232 0 0 YYYYYYYYYYY.YYYYYYYY.covad.net YY.YYY.
46.186
Dec 27 10:06:20 nameserver2 popper[18926]: Stats: XXXXXXX 0 0 0 0 0 0
XXXXXXXXXXXXXXXX.nycmny.east.verizon.net XX.XX.
20.XX
With the numbers being (in order)
Number of messaged downloaded
Number of bytes downloaded
Number of messages deleted
Number of bytes deleted
Number of messages left
Number of bytes left