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In September 2021, we announced that effective October 1, 2022, we 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.
– https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online#when-will-this-change-take-place
“Basic Auth" or “basic authentication” means authentication with only a user name and password. See What is SMTP AUTH? below.
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