These notifications are being sent to you from the mail server indicating that delivery of the message has been delayed.

The server of either your mail system or the recipient's mail system may be set up on batch processing or is having other difficulties.

You can try emailing the postmaster from which the notification came (that email address will be on the notification). However, the best practice is normally to just be patient and wait for the message to eventually be delivered. The only cause for concern is if you receive a notification that states there was a permanent delivery failure or if you continue to receive notifications about delays over an extended period of time (weeks).

OUTCOME

Email will eventually be delivered.