Fix Microsoft 365 Email Cannot Be Added as IMAP or POP3
Question details
Users are unable to connect to their Microsoft 365 mailboxes using POP3 or IMAP protocols because the connections are rejected.
- Product
- Microsoft 365 / Exchange Online
- Device & OS
- not provided
- Scenario
- Attempting to add a Microsoft 365 email account to an email client using manual IMAP or POP3 settings.
- Observed behavior
- The email client fails to authenticate and sign in, even if POP3 and IMAP protocols are enabled in the Microsoft 365 admin center.
Ensure you know your Microsoft 365 account credentials and have access to the latest version of your preferred email client.
Upgrade to an Email Client with Modern Authentication (OAuth2)
Microsoft has deprecated Basic Authentication for Exchange Online. Upgrading to a client that supports Modern Authentication is required to connect to Microsoft 365.
Older email clients that only support username and password (Basic Authentication) for IMAP and POP3 can no longer connect to Exchange Online. Transitioning to a client that supports OAuth2 is the official resolution.
Verify if you are using an outdated email client such as older versions of Outlook (2013 or older), legacy Thunderbird, or outdated native mobile mail apps.
Download and install an email client that explicitly supports Modern Authentication, such as Microsoft Outlook (Microsoft 365, 2016 or newer), the latest Mozilla Thunderbird, or Apple Mail (macOS 10.14+ / iOS 11+).
When adding your account in the new client, choose the 'Microsoft 365' or 'Exchange' option instead of manually selecting IMAP or POP3. This forces a secure Microsoft login prompt (OAuth2).
Configure Correct IMAP/POP and SMTP Server Settings
If your updated email client requires manual configuration, you must input the exact server addresses and encryption methods mandated by Exchange Online.
Enable Authenticated SMTP in Microsoft 365 Admin Center
Even if the incoming mail works via Modern Authentication, the email client may fail to send messages if Authenticated SMTP is disabled for the user.
Try WPS Office as Your Lightweight Productivity Suite
If complex Exchange server configurations and Microsoft 365 authentication changes are disrupting your workflow, consider using WPS Office for your local document needs. It provides a comprehensive, lightweight, and free alternative for Word, Excel, and PowerPoint files without the hassle of online sync issues.
Frequently Asked Questions
Why did my POP3/IMAP email suddenly stop working in Microsoft 365?
Microsoft officially deprecated Basic Authentication (username and password only) for Exchange Online to enhance security. If your email client does not support Modern Authentication (OAuth2), Microsoft 365 will reject the connection.
Can I re-enable Basic Authentication for my Microsoft 365 tenant?
No. Microsoft has permanently disabled Basic Authentication for Exchange Online across all tenants for protocols like POP3, IMAP, and EWS. You must migrate to an email client that supports Modern Authentication.
What email clients support Modern Authentication for Microsoft 365?
Most current email clients support Modern Authentication. This includes Outlook (Microsoft 365, 2021, 2019, 2016), recent versions of Mozilla Thunderbird, Apple Mail on macOS 10.14+ and iOS 11+, and the default Android Gmail/Mail apps.
Does SMTP still work with Basic Authentication in Microsoft 365?
Microsoft still allows SMTP AUTH for sending emails in certain legacy scenarios (like printers or scanners), provided it is explicitly enabled in the Microsoft 365 Admin Center. However, upgrading to Modern Authentication is strongly advised.
