Sending, receiving, and organizing email in Outlook.com
Your church's IT folks may likely need to setup DMARC with their DNS provider and their Exchange service. I looked up the MX (mail server) records and found that it was not setup. You can also add your church as a "Safe Sender", so even if they don't fix it, by setting up DMARC, their emails will not go to your spam. See https://support.microsoft.com/en-us/outlook/mail/add-recipients-to-the-safe-senders-list-in-outlook for details on how to add them as a safe sender.