Hi! Whe scheduling a meeting everything works just fine, but the email that is opened is just an email, not an appointment. Why not provide an ics file? This would work with any email system.
In Thunderbird, I import the ICS file via import and then, I may invite people on this entry.
The german import menu entry is "Termine & Aufgaben"->Import
Yes, it is really annoying. Each time I press something on Teamviewer Meeting, the not uninstallable Outlook is opening. They don't have a mapi interface included which may work with thunderbird and other mail clients to.
Good news is that an ics file is written and put on the hard drive. The path is:
C:\Users\<your user name>\AppData\Roaming\TeamViewer
Hope this helps,
Harald