First make sure the emails have not ended up in the supporters Junk mail or Spam folders as they may have received them in these folders.
Next You can run a report to check email addresses that have been added to our Blacklist. You can review the reasons an email may be Blacklisted.
If the email address is on the Blacklist you can request the email be removed by contacting support or submitting a case on Case Central.
If an email has been blacklisted it will not be sent to that email.

If you have done all of the above and still need to verify the emails we sent out contact support or submit a case on Case Central with the following information:
  1. Email recipient's name
  2. Email address of the recipient
  3. Date the email was sent out from Sphere
  4. Email Campaign/Event Name

Support will research if our logs show the emails were sent successfully or not.