Check the email addresses, subject line, and date, and run the checks again. If that doesn't work, contact the sender and ...


Check the email addresses, subject line, and date, and run the checks again.

If that doesn't work, contact the sender and ask if they received an email that explains why the message wasn't delivered (non-delivery report). The problem seems to be happening before the message arrives at the Office 365 mail servers. You might want to verify that your organization's mail servers have been correctly set up to send mail to Office 365. Follow these steps:
  1. Go to the connectors page.
  2. Choose the Check to see if you should create a connector link in the first paragraph, and follow the step-by-step instructions.