iCloud 
Resend shared calendar invitations
As the owner of a shared calendar, you can resend invitations to all or selected participants at any time. You may want to do this if you’re tracking invitation responses and notice some invitees haven’t yet responded.
Resend invitations
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Click the Share button to the right of the calendar’s name.
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Do one of the following:
For a private calendar, click the pop-up menu with the invitee’s name, then choose Invite Again.
For a public calendar, click Email Link, type the participant’s email address in the To field, then click Send.