Znuny/Znuny LTS is a fork of the ((OTRS)) Community Edition, one of the most flexible web-based ticketing systems used for Customer Service, Help Desk, IT Service Management.
Consider removing MentionSeen flags similar as for Seen flags (i.e. on ticket archiving and possibly other appropriate events) to avoid keeping it forever in table (if not required).
For Znuny 6.5+:
Consider removing MentionSeen flags similar as for Seen flags (i.e. on ticket archiving and possibly other appropriate events) to avoid keeping it forever in table (if not required).