POP3 Authentication with OAuth gives “Err Protocol error. Connection is closed”
问题 My company needs to upgrade an application to integrate two-legged OAuth 2.0 for POP3. I'm testing with an outlook online account and trying to authenticate on outlook.office365.com (I've also tried pop3.live.com). I registered for an Exchange Online trial using my test outlook account. I've registered my app on Azure and have enabled API Application Permissions for MS Graph (Mail.ReadWrite, Mail.Send) and Exchange (full_access_as_app). The same outlook account I used for the Exchange