If your WordPress website has stopped sending email to Outlook 365 accounts, you’re not alone. Over the past year, Microsoft has tightened email security and authentication requirements, and many WordPress sites that relied on default email behavior have been affected.
This guide outlines a clear, reliable process for configuring WordPress to send email through Outlook 365 using the WP Mail SMTP plugin. It also clarifies which tasks belong to the web developer and which require an Outlook 365 administrator.
Why WordPress Email Stops Working with Outlook 365
By default, WordPress sends email using the PHP mail function. These emails are unauthenticated and no longer reliably accepted by Microsoft 365. Outlook 365 now expects modern authentication, proper domain alignment, and validated DNS records. If those requirements are not met, messages may be rejected silently or never delivered.
The solution is to route WordPress email through Outlook 365 using authenticated SMTP with OAuth, which is exactly what WP Mail SMTP enables.
Tools and Access Required
Before starting, confirm you have the following:
- WordPress admin access
- WP Mail SMTP plugin installed
- Microsoft 365 Global or Exchange Admin access
- DNS access for the sending domain (often managed via Cloudflare or a registrar)
Step-by-Step Setup: WP Mail SMTP with Outlook 365
Step 1: Install and Configure WP Mail SMTP
Owner: Web Developer
Install and activate the WP Mail SMTP plugin in WordPress. Navigate to WP Mail SMTP settings and configure the sending details:
- Set a valid From Email address using your domain, such as
- Enable the option to force the From Email
- Set a clear From Name that matches the website or organization
This ensures all WordPress emails use a consistent, authenticated sender.
Step 2: Select the Outlook Mailer
Owner: Web Developer
Within WP Mail SMTP settings, choose Outlook as the mailer and save your settings. Do not enter a username or password. Outlook 365 will be authorized using OAuth instead of basic authentication.
Step 3: Authorize Microsoft 365 (OAuth Connection)
Owner: Outlook 365 Admin
Click the Authorize button in WP Mail SMTP. Log in using a Microsoft 365 admin account and approve the requested permissions. This process creates an Azure application automatically and enables modern authentication without storing any passwords in WordPress.
Step 4: Enable Authenticated SMTP for the Mailbox
Owner: Outlook 365 Admin
In the Microsoft 365 Admin Center, open the sending mailbox’s settings and ensure that Authenticated SMTP is enabled for that user. This setting is required even when OAuth is used.
Step 5: Enable DKIM for the Domain
Owner: Outlook 365 Admin
DNS Changes: Web Developer (if DNS is externally managed)
In the Exchange Admin or Microsoft Defender portal, enable DKIM for the sending domain. Microsoft will provide two CNAME records that must be added to DNS. These records allow Outlook 365 to cryptographically sign outgoing messages, which significantly improves deliverability.
Step 6: Verify or Update the SPF Record
Owner: Web Developer
Ensure the domain’s SPF record includes Microsoft 365 as an authorized sender. A basic multi-recipient example looks like this:
v=spf1 include:spf.protection.outlook.com include:mailgun.org include:spf.wpengine.com -all
