When I receive meeting invitations to my Gmail account they appear as regular mails with an attachment. Opening the message in Gmail lets me add the event to my Google Calendar, making it appear in OS X Calendar after the next sync.
However, when I receive invitations to my Office 365 account they appear in OS X Calendar "incoming invitations" menu bar item. They also show up as grey tentative bookings in the calendar.
Why don't Gmail invitations work like Office 365 invitations? Can I make Gmail invitations appear in OS X Calendar?
N.B., I don't use the Gmail account in Mail.app, but I do use the Office 365 account there.