calendar invites not sent outside contacts list

Hi - I am trying to send a calendar invite

  1. from email I click “Create meeting from message”
  2. Calendar invite opens BUT the Participants list is not populated
  3. I add participants to the list 
  4. Some participants are in the contacts list
  5. SOme participants are not in the contacts list and i add emails only
  6. Save
  7. Send

Now - the participants who were in the contacts list get the invite but others dont

This is happening from my live.com IMAP mail and GMAIL - tested on both. 

Please advise

Thanks

GM

Hello Gaurav,
mail invitations are handled by the mail server.
Are you sure that the other participans did not get invited or did they just not see the invitation in their inbox? Perhaps it has been synchronized to their calendar?
Does it perhaps depend on the mail address of the participant? Microsoft/gmail/apple accounts?
Any additional detail will help us greatly in figuring this issue out.

Regards,
Olivia