I'm getting this error when trying to send an email to my outlook.com address

Subject: HELLO THERE

 

This message hasn't been delivered yet. Delivery will continue to be attempted.

 

The server will keep trying to deliver this message for the next 1 days, 19 hours and 55 minutes. You'll be notified if the message can't be delivered by that time.

 

Same results when my coworker tries to send me an email as well.