1.0 (05.09.18)
# First release
1.1 (1/5/19)
# added user roles authorization permission, now you dont use -1 to unlimited messages => uncheck limits on user roles page (section: mailbox)
# optimize plugin code
1.2 (6/5/19)
# fix bug with users with default role only
# fix bug with counting chat messages
# fix bug with limit messages, where users can store limit + 1 message