Megan:

Something has changed.

Did you download and install any Microsoft updates (this might be setup to happen in the background)?

We are finding the ISP's are now requiring external generators of emails (aka Adagio Invoices) to require authentication and a change in port numbers. Also auto generated emails are getting blocked as spam more often. Check with your email provider.

As a test, try changing the Adagio email setup to MAPI.

Other than that, this is a difficult problem to troubleshoot over the forum.