Invitations by email

I am a new user of Zoho Calendar. Can you please explain the details of how to invite people to events.

Please confirm that you can send an invite to ANY email address. The person you invite does not need to be already registered on Zoho.

I tried sending several invites to a test addresses, but they never arrived. This is the method I used. Edit the event, open the Invitation box and type the email address. Then click Save. I could see no indication that an email was being sent. Am I missing something? When I opened the event again, the email address was no longer in the Invitation box.

Can you please help. Bob