I have found a problem running a incremental backup of all accounts, only backups mails of the current day, and other issues like send mails of full backups of new users, because a filter of sessions.txt is not working ok.

The problem was fixed changing the line #350 in zmbkpose file

•   INCFROM=$(grep INCFROM: $WORKDIR/sessions.txt | tail -1 | awk '{print $2}')
  

•    INCFROM=$(grep $MAIL $WORKDIR/sessions.txt | tail -1 | awk '{print $2}')