RE: 'Invalid Email address for recipient of type Contact'
Hi Ted,
According to the error message you provided, this error occurs if there was an invalid email address included on the To or Cc line of the email.
Please review the email message that encountered this error and verify all email addresses on the To and Cc lines are valid email addresses.
Also, the id of the contact is kind of weird. Please try to check if there is a contact whose id is "00000...00000" in your environment.
The id can be found in the URL of the contact.
E.g. "...?appid=474563ef-34a0-ec11-b400-000d3a34c22d&pagetype=entityrecord&etn=contact&id=01d72acf-e8e9-4ae3-bf4b-9ba2ef1c5367"
If the above does not solve the problem, please click on Show Details in the picture to see if there is an error log available to me.