KB08081301 Updating Calendaring
Up to and including Mailtraq 2.12, Mailtraq used a proprietary calendar system - which works well, but it predates the widespread adoption of the now generally used iCal standard - and it is not compatible with iCal.
Mailtraq 2.12 is the last to use the old system, and 2.14 uses iCal
Moving from Mailtraq Calendaring to iCal
Mailtraq MOS migrates the entries from the old system to the new one without User involvement. Generally there are no issues associated with this updating, however there are circumstances - such as reverting to a previous build that can complicate the issue.
However it should be straightforward to correct, as the old entries and the new entries are held in separate files in the Calendaring system. In this location: C:\Program Files\Mailtraq\database\calendars
Mailtraq build 220.127.116.116, and above, supports the manual import of Calendars.
If certain users have missing information, then you can go into the Console and import their calendar from the files offered - iCalendar File or Mailtraq Calendar File.