The LiveJournal ‘sysban’ mechanism provides the means for generic bans on site functionality given a block type and value. The type is what is being checked (IP address, email address, etc) and the value is the value which causes the block to activate. (10.0.0.10, for example)
A tool is available to create and modify bans: $LJHOME/htdocs/admin/sysban.bml. This tool requires the sysban privilege.
The most notable of the three is the sysban_trig type. The data it logs varies depending on the type of ban and the information available when it was triggered. If a userid is available, it will be logged and the notes column will contain a short description of what caused the trigger along with a number of variables that may be useful in investigation of the situation.
Below are the ban types that exist as of now. More can and will be added as necessary:
Blocked if email matches.