The default procmail configuration records actions in $HOME/.procmail/log . To prevent the log files from getting large enough to waste space and interfere with users' disk quotas, we "age out" these files.
If
you have a file named $HOME/.procmail/logthen
and that file is at least 300k in size
and it has been a month or more since the last time your logs were rotated
your log will be compressed (gzip) and renamed log.0.gz. Up to three most recent versions of the logfile (log.0.gz, log.1.gz, and log.2.gz) will be retained - older logs will be deleted.
If you don't want your logs rotated and you don't want to change the
name of your log you can avoid rotation by creating a file called
".norotate" (don't forget the leading period) in your home directory.
This sequence of commands
cd
touch .norotate
You can see discussion of this topic dating from October 2002 under the subject "Rotating old procmail logs" in the newsgroup panix.upgrade.