How to Fix Exchange SMTP Authentication Fails for IMAP and SMTP
Question details
The user is unable to configure an Exchange email account via IMAP and SMTP on an online portal, receiving errors that no account or settings were found despite SMTP being enabled.
- Product
- Microsoft Exchange
- Device & OS
- not provided
- Scenario
- Configuring a Microsoft Exchange email account on a third-party online portal using IMAP and SMTP.
- Observed behavior
- The portal reports that no account or settings are found, causing the connection to fail, even though SMTP is enabled and modern authentication is disabled.
Ensure you have administrator access to your Microsoft 365 tenant and that Exchange Online PowerShell is installed on your system.
Reset Basic Authentication for POP and IMAP via PowerShell
Toggle the Basic authentication settings in your Microsoft 365 tenant to resolve hidden configuration conflicts blocking IMAP and SMTP.
Even when SMTP appears to be enabled, underlying tenant policies might block legacy authentication methods. Resetting the Basic authentication status for POP and IMAP forces the server to refresh these permissions.
Open PowerShell as an administrator and connect to Exchange Online using your tenant admin credentials.
Check if Basic authentication is currently enabled for POP and IMAP protocols within your tenant settings.
If it is already enabled, run the appropriate PowerShell command to disable Basic authentication for both POP and IMAP temporarily.
Pause for a few minutes to allow the updated authentication policies to propagate across the Microsoft 365 servers.
Execute the PowerShell command to re-enable Basic authentication for POP and IMAP, then attempt your portal configuration again.
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Frequently Asked Questions
Why does Exchange IMAP/SMTP authentication fail when SMTP is enabled?
Even if SMTP is enabled on the mailbox, the tenant's overall authentication policies, such as disabled Basic authentication, can block connections from third-party portals.
How do I check my Exchange tenant authentication settings?
You can verify your tenant's authentication policies by logging into the Microsoft 365 admin center under Org Settings, or by querying the authentication policies using Exchange Online PowerShell.
Do I need PowerShell to fix IMAP/SMTP connection issues?
In many cases, yes. Resetting or explicitly defining authentication policies for specific legacy protocols often requires Exchange Online PowerShell for granular control.
What should I do if resetting Basic authentication doesn't work?
If the issue persists, capture a detailed screenshot of the exact error message, verify that no Conditional Access policies are blocking legacy authentication, and consult Microsoft's official troubleshooting documentation.
