Recipient: {0} If you used the intended recipient address, they're not receiving email because they don't exist in your email ...

Recipient: {0}
If you used the intended recipient address, they're not receiving email because they don't exist in your email system. To fix this, you need to add them to Office 365 using the following steps.
  1. In the Office 365 Admin center, go to the Users and Groups page.
  2. Choose Add a user (Add icon).
  3. Provide the requested information, and a mailbox is created automatically for the new user.