Microsoft 365 Basic Authentication End of Life: Fix Your Email Now

Are you having trouble sending email via Outlook SMTP?

If you’ve come across an error message suggesting that basic authentication is disabled for your Outlook or Microsoft 365 account, you need to update your SMTP settings. 

Microsoft has begun shutting down Basic Authentication—using a typical username/password pair—for apps and services (like WordPress plugins) that send emails through SMTP.

From now on, OAuth (Modern Authentication) is mandatory to keep using your Outlook, Hotmail, or Microsoft 365 account to send emails from your website.

In this guide, I’ll walk you through why Microsoft made this switch, what it means for your WordPress site and how to continue sending emails without interruption

Is Your Website Affected?

You may be impacted if:

• You’re getting SMTP authentication errors when sending emails.
• You’ve set up Easy WP SMTP using your Microsoft 365 or Outlook username and password in the “Other SMTP” mailer or you’re using the basic SMTP settings in any email plugin or app.

Your emails might be failing and returning an error message like the following:

535 5.7.139 Authentication unsuccessful, basic authentication is disabled.

However, if you’ve previously connected to your Microsoft 365 / Office 365 email account using your standard username and password in the Other SMTP mailer, you’ll need to follow the directions below to change to the 365 / Outlook Mailer.

Don’t worry – with our one-click connection, your account will be set up and sending emails securely again within minutes!

How to Fix Outlook Basic Authentication Errors

Use a Plugin That Supports OAuth

To keep sending emails from your WordPress site through Outlook, Hotmail, or Microsoft 365, you’ll need an SMTP plugin that can handle Modern Authentication.

If you’re currently using username/password fields in Easy WP SMTP (or another plugin), it’s time to switch to the Microsoft 365 / Outlook mailer option in Easy WP SMTP, which uses OAuth tokens to verify your account more securely.

Send WordPress Emails With Outlook and Easy WP SMTP

You can access the Microsoft 365 / Outlook mailer with any paid Easy WP SMTP plan. To get started, just go to the pricing page and choose the plan that’s most suitable for the number of sites you’ll be using it on.

You can follow our Getting Started guide for step-by-step instructions on how to install the plugin

In Easy WP SMTP plugin setup, select “Microsoft 365 / Outlook” as your mailer to connect your WordPress site using OAuth. This ensures your credentials are never directly stored and are exchanged for temporary tokens instead.

While setting up a connection to your Microsoft account with OAuth is normally quite time-consuming and technical, we’ve made things super easy for your with our One-Click Setup option.

Just make sure to turn One-Click Setup to ON in the plugin settings.

You can see more detailed instructions in our guide to one-click Outlook setup.

Why Did Microsoft Phase Out Basic Authentication?

Microsoft’s primary motive is boosting security. Basic Authentication methods are vulnerable because they rely on static passwords that can be exposed or stolen.

Modern Authentication uses OAuth 2.0, which generates short-lived tokens that can be revoked at any time, minimizing the potential for unauthorized access.

After gradually encouraging users to switch, Microsoft has confirmed Basic Authentication will be completely retired by September 2025. This change ensures more robust protection against hacking attempts and secures user accounts.

What Exactly Is Modern Authentication?

Modern Authentication is a safer, token-based access method. Instead of permanently storing passwords, apps request a limited-time “token” that lets them send emails or perform other specific tasks in your account. Key benefits include:

• Enhanced Security: Passwords are never shared directly, and tokens can be invalidated if needed.
• Granular Permissions: Only certain functionalities (like sending emails) are authorized, reducing the risk of a full account compromise.
• Multi-Factor Authentication Compatibility: You can add extra layers of login security, making it harder for unauthorized users to gain access.
• Higher Deliverability: Email services often prioritize traffic from senders using secure protocols.

Modern Authentication isn’t solely about securing email-sending. The extra security features like Multi-Factor Authentication and Conditional Access Policies helps prevent account compromise and reduce phishing risks, benefiting every aspect of your Microsoft account usage—not just your emails.

Considering Alternatives to Microsoft Email Services

Although Microsoft 365/Outlook is easy to set up with our one-click setup option, some users might prefer to consider other options for sending their WordPress emails.

If so, you can explore other email providers that integrate seamlessly with Easy WP SMTP:

• SendLayer
• Gmail or Google Workspace
• SMTP.com
• Brevo
• Mailgun
• Amazon SES
• SendGrid
• Postmark
• SparkPost
• SMTP2GP
• Zoho
• Mailjet
• Elastic Email
• Other SMTP

Each service has unique advantages like free monthly sending limits, easy setup, and different security features. You are free to pick an email provider that fits your needs and budget.

Frequently Asked Questions About the Retirement of Basic Auth

Do you have more questions about Microsoft stopping support for basic authentication? Here are some of the most common questions our support team has received about using Outlook and Microsoft 365 / Office 365 email with WordPress:

Transitioning from Basic Authentication to Modern Authentication is essential to keep your Outlook or Microsoft 365 emails working and ensure the security of your account.

With Easy WP SMTP’s One-Click Outlook it’s now simple and easy to use Modern Authentication with OAuth to connect your WordPress site to your Outlook email account.