Emails not going through to Microsoft Office 365 Users

Starting 3/6/24 at 3:30 CST I could not receive any test emails in Outlook. I sent to external users Outlook and same issue. Earlier in the week I had no problem testing the same campaign. Support told me to create a new template which I did from scratch but still have the same issue. This seems similar to an issue reporting in January by another user related to Outlook Protection, but is there anything I can do?