Fix Microsoft SMTP Authentication Error
Written on by Shipi.
Quick Solution
If you're encountering the error:
535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Tenant.
The easiest way to resolve this is by enabling SMTP authentication for your Microsoft 365 account.
Step 1: Enable SMTP Authentication in Microsoft 365
-
Go to the Microsoft 365 Admin Center.
-
Navigate to Users > Active Users.
-
Select the user account you're using for SMTP authentication.
-
Under Mail > Manage email apps, ensure Authenticated SMTP is checked.
-
Click Save Changes.
Step 2: Use an App Password (if MFA is Enabled)
If Multi-Factor Authentication (MFA) is enabled for your account:
-
Sign in to Microsoft Security.
-
Go to Security Info > Add sign-in method.
-
Select App password and follow the instructions.
-
Use this app password instead of your regular password in Shipi.
Start with Our Free Plan
Shipping rates, store integration, and 100 order shipments - yours for a lifetime!
*No credit card required
Create Free Account