I have gone into Tools->Options->Content Viewers and associated .vcs and .ics extensions to pmical.exe. When I get an email with an attachment with one of these extensions, clicking Open opens it with pmical.exe.

I receive many Teams invitations that have an attachment called Calendar that has no extension. The description given to it by Pegasus is "Calendar invitation or information".

I have tried adding to "content viewers" an 'Attachment type' information that matches "Calendar invitation or information" . I also tried this and added .ics as the extension for Temporary File Handling. This did not work.

Is there a way to get pmical.exe to open these files?