.ics files should be whitelisted as file types for upload
Currently an uploaded .ics file to Civi has the 'unknown' suffix appended. To offer some background, .ics file is a common format used by Google, Outlook and many other calendar software https://en.wikipedia.org/wiki/ICalendar. Indeed you will see this filetype attached to many email invitations you get for meetings.
I suggest that this filetype should be whitelisted by CiviCRM and uploaded without modification, for use in all places where attachments are allowed: CiviMail, custom data fields, etc. Since the filetype contains only data (similar to JSON or XML) there are no security issues I'm aware of, but I will rely on security experts to judge ultimately be the judge. Here's an example of part of the problem CiviCRM's appended suffix causes. The ".unknown" file cannot be recognized nor easily opened. @eileen @seamuslee