In September 2021, Microsoft announced that effective October 1, 2022, they will begin disabling Basic authentication for Outlook, EWS, RPS, POP, IMAP, and EAS protocols in Exchange Online. SMTP Auth will also be disabled if it is not being used. See full announcement: Basic Authentication and Exchange Online – September 2021 Update.
The available options for transitioning from Basic Authentication to OAuth 2.0 are:
Modern Authentication (Connect Button)
Exchange Web Services (Azure App)*
* According to the Exchange Team Blog, the AppID Allow List is a temporary solution and will only work until April 1, 2027. After that date, Microsoft will fully disable EWS in Exchange Online, so migration to the Microsoft Graph API will be required.
This integration will be supported and maintained until October 1, 2026, but creating new integrations will be disabled beginning September 1, 2024 in the MeetingRoomApp Cloud.