mlmmj-bounce is used to handle mails that are bouncing. When a mail arrives to the system, mlmmj-bounce
will register in <listdir>/bounce/<addrstring> info about which number that bounced at what time. An
example of such a line could be:
109:1094409801 # Sun Sep 5 20:43:21 2004
The above shows that message number 109 bounced 1094409801 seconds after epoch which is in human date
stamps is Sunday September 5th 20:43:21 2004.
The last bounce mail received to the address is saved in <listdir>/bounce/<addrstring>.lastmsg.
When the -p option is used it sends out a probe email including info that it's a bounce probe and a list
of the bounced message numbers. The existance of a <listdir>/bounce/<addrstring>.probe file indicates
that a probe have been sent out.