Receiving Email with Subject "Undeliverable: You Have Notifications Pending"

This error is a "bounce" notification generated when a sent message does not reach the recipient.

Issue

You receive an email similar to the one below:

Cause

This is a standard "mail bounce" notification from Microsoft Office 365, sent when an email fails to reach its intended destination.

Resolution

To resolve this issue:

• If you did send the message referenced in the bounce notification, follow the instructions provided. 
• If you did not send the message, this bounce notification is a sign that your email account has been compromised. Immediately change your password as a preventative measure.