Exchange Connection Problems

How to Fix Microsoft 365 Exchange POP3 or SMTP Authentication Failure in Gmail

Huma Ashraf Ch Oct 1, 2026 869 views

Question details

Users are unable to successfully authenticate their Microsoft 365 Exchange email accounts in Gmail via POP3 or SMTP, despite using the correct server settings and credentials.

How to Fix Microsoft 365 Exchange POP3 or SMTP Authentication Failure in Gmail

Product: Microsoft 365 Exchange, Gmail
Device & OS: not provided
Scenario: Adding or syncing a Microsoft 365 Exchange work or school account within the Gmail app or Gmail web interface.
Observed behavior: Gmail rejects the connection with an authentication error because Microsoft 365 security defaults, OAuth requirements, or tenant settings are blocking basic authentication.

Before you start

Ensure you have your Microsoft 365 administrator's contact information handy, as resolving basic authentication blocks often requires tenant-level administrative privileges.

Solution 1Recommended

Add the Account Using the Modern Exchange/OAuth Option

Bypass basic POP3/SMTP authentication limits by utilizing the modern OAuth integration directly built into Gmail.

Microsoft heavily restricts basic authentication for security purposes. Using modern authentication (OAuth) is the most reliable way to connect your Microsoft 365 account to third-party clients like Gmail.

Open Add Account Settings

Launch the Gmail app or web interface, navigate to Settings, and select 'Add account'.

Select the Correct Provider

Instead of choosing 'Other (POP3/IMAP)', tap on 'Exchange and Office 365' or 'Outlook, Hotmail, and Live'.

Complete Modern Authentication

Follow the on-screen prompts to log into the Microsoft portal. This will authenticate your account securely using OAuth without relying on basic POP3/SMTP passwords.

Add the Account Using the Modern Exchange/OAuth Option

OAuth Authentication: Using the Exchange option ensures your connection complies with Microsoft's modern security defaults automatically.

Solution 2

Verify Mailbox Security Policies with Your IT Administrator

If you must use POP3 or SMTP, your Microsoft 365 tenant administrator must explicitly allow these older protocols.

Solution 3

Confirm Manual Server Names and Ports

Double-check your manual POP3 and SMTP configurations to ensure no typographical errors are causing the rejection.

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Frequently Asked Questions

Why does Gmail say my Microsoft 365 authentication failed when my password is correct?

Microsoft 365 has disabled basic authentication by default across all tenants to improve security. Even with the correct password, Gmail's traditional POP3/SMTP connection attempts are blocked. You must use modern OAuth authentication to sign in successfully.

How do I know if my Microsoft 365 admin disabled SMTP authentication?

If you repeatedly receive authentication errors despite having the correct credentials and server settings, basic authentication is likely disabled. Your IT administrator can confirm this by checking your mailbox settings and Azure Active Directory sign-in logs.

Can I use IMAP instead of POP3 for my Microsoft 365 account in Gmail?

Yes, but IMAP is subject to the same basic authentication restrictions as POP3 and SMTP. To use IMAP, your organization must explicitly allow it, or you should select the 'Exchange and Office 365' option in Gmail to utilize modern authentication.

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