Unable to send email message in ESC from Office/Outlook365 or other Azure-based Exchange Servers

Error Sending: Unable to send email message: failure sending mail.

Email management distribution of Office/Outlook365 and other off-site email
exchange servers have, by default, disabled Legacy TLS protocols and enabled LMFA
(Multifactor Authentication) settings in your server settings and Microsoft Windows
workstations. These changes have disabled the current version of ESC to properly send
emails from them. ESC 15.14 and lower require TLS securities to be enabled to relay
email.

You will have to reenable these changes on your email exchange server and your
Microsoft Windows workstations.

Note: These steps are for Office365 Exchange Servers, it is
recommended you reach out to your email host company regarding their
default settings and assistance.

1. Reenable Legacy TLS 1.2
   • Server-side: https://docs.microsoft.com/en-us/mem/configmgr/core/plan-design/security/enable-tls-1-2-server
   • Windows client-side: https://docs.microsoft.com/en-us/mem/configmgr/core/plan-design/security/enable-tls-1-2-client
2. Disable Legacy per-user MFA:
   • https://docs.microsoft.com/en-us/microsoft-365/admin/security-and-compliance/set-up-multi-factor-authentication?view=o365-worldwide#turn-off-legacy-per-user-mfa