UPDATE: For investigation, I did alias of this unknown address to my work mail, get this messages, and that is what I see:
1. Sender: Cron daemon
2. Subject of message: "Cron <amavis@mail> test -e /usr/sbin/amavisd-new-cronjob && /usr/sbin/amavisd-new-cronjob sa-sync"
3. Text content of message: "Wide character in print at /usr/share/perl5/Razor2/Logger.pm line 107."