Email Integration with Microsoft 365
This also applies to Outlook 365 and Office 365 - basically follow this if using Microsoft to host your email.
Log in to https://admin.microsoft.com
Click the icon in the top-left corner with three lines. Expand 'Users' and click 'Active Users'.
Click the username who you want to permit to send emails through Retreat Manager. Once the user is selected click 'Mail' in the pop-out on the right. Then click 'Manage email apps'.
Click all of the boxes. Then click Save Changes button at the bottom.
Continue with the steps in the Email Setup Tutorial: https://www.retreatportal.com/post/retreat-manager-email-setup