Microsoft 365 has disabled Basic Authentication (Basic Auth) by default for security reasons. This type of authentication, which only requires a username and password, is more vulnerable to attacks such as credential theft and brute-force attempts. For this reason, Microsoft encourages the use of more secure authentication protocols like OAuth 2.0. However, if necessary, you can manually enable Basic Auth to configure an SMTP server.
To configure an SMTP server with Microsoft 365 using Basic Authentication, follow these instructions:
- SMTP Host: smtp.office365.com
- Port: 587 (STARTTLS) or 25 (STARTTLS)
- Authentication: Username and password of your Microsoft 365 account
Note: Before configuring the SMTP server, make sure to enable Basic Auth via the Microsoft 365 admin panel. This is required to allow SMTP connections.
Key Steps:
- Log in to the Microsoft 365 admin portal (admin.microsoft.com).
- Navigate to "Settings" and select "Security Settings."
- Enable Basic Authentication for the SMTP protocol.
- Save changes and wait for propagation.
Use the Microsoft 365 admin center to enable or disable SMTP AUTH on specific mailboxes
- Open the Microsoft 365 admin center and go to Users > Active users.
- Select the user, and in the flyout that appears, select Mail.
- In the Email apps section, select Manage email apps.
- Verify the Authenticated SMTP setting: unchecked = disabled, checked = enabled.
- When you're finished, select Save changes.
