Troubleshooting Email Errors: Enabling IMAP and SMTP Access in Office 365

This article outlines troubleshooting steps for common errors and messages encountered during the setup and configuration of custom emails using IMAP and SMTP.

Log in to the Microsoft 365 admin portal at https://admin.microsoft.com/ as an administrator. Navigate to the Org settings screen and locate the Modern authentication entry:

• Enable ‘Turn on modern authentication’ for OAuth flows.
• Enable IMAP, and SMTP for App passwords flows.

Next, proceed to the Users screen:

• Select a user and click on the Mail tab.
• Click on Manage email apps.

• Enable IMAP, POP, and authenticated SMTP to activate these protocols for the selected account.

Please note that changes may take 20-30 minutes to take effect.

Exchange administration
You can find the same mailbox/user settings through Exchange administration screens: