Outlook Error Codes

How to Fix Outlook Error 5.7.57 Client Was Not Authenticated

John Wilson Sep 28, 2026 870 views

Question details

The user needs to resolve an SMTP error preventing them from sending emails due to unauthenticated client status.

How to Fix Outlook Error 5.7.57 Client Was Not Authenticated

Product: Microsoft Outlook / Exchange
Device & OS: not provided
Scenario: Sending an email from a multifunction device, application, or email client through Microsoft 365 or Exchange.
Observed behavior: Outlook or the sending application reports SMTP error 5.7.57, indicating that the client was not authenticated to send anonymous mail during the MAIL FROM command.

Before you start

Before troubleshooting, confirm your email account type (Microsoft 365, Exchange, IMAP, POP, or Outlook.com) and ensure you have the correct account credentials available.

Solution 1Recommended

Verify SMTP Authentication and TLS Settings

Ensure your application or device uses the correct SMTP server settings, valid credentials, and supports TLS encryption for Exchange Online.

This error most commonly occurs when an application or multifunction device is improperly configured for SMTP client submission using smtp.office365.com.

Check the SMTP Server Address

Access your application or device's email settings and verify that the SMTP server is set to 'smtp.office365.com'.

Verify Port Settings

Ensure the SMTP port is configured to 587 (recommended) or 25.

Enable TLS Encryption

Check the box or select the option to require a secure connection (TLS or STARTTLS). Error 5.7.57 often triggers if the sending device does not support or enable TLS.

Re-enter Account Credentials

Input the full email address and password of a valid Microsoft 365 mailbox to ensure the client is properly authenticated.

Verify SMTP Authentication and TLS Settings

App Passwords and MFA: If your Microsoft 365 account has Multi-Factor Authentication (MFA) enabled, you must generate an App Password in your security settings and use it instead of your regular password for SMTP authentication.

Solution 2

Configure Microsoft 365 Direct Send or SMTP Relay

If your device does not support TLS or you need to send emails from multiple addresses, use an alternative connection method like Direct Send or an SMTP Relay.

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Frequently Asked Questions

What does SMTP Error 5.7.57 mean?

Error 5.7.57 means your email client, multifunction device, or application attempted to send an email without providing the necessary authentication or TLS encryption required by servers like Microsoft 365 or Exchange Online.

Why is my multifunction printer getting error 5.7.57 suddenly?

Multifunction printers often encounter this error if they do not support TLS encryption, if the email account password has expired, or if Multi-Factor Authentication (MFA) was recently enabled on the account. Using an App Password or setting up an SMTP relay connector can resolve it.

Can I use a personal Outlook.com account to fix this issue?

Personal Outlook.com accounts have different SMTP settings and stricter automated sending limits compared to Microsoft 365 work accounts. For devices like scanners or web applications, a dedicated Microsoft 365 mailbox is strongly recommended to ensure reliable authentication.

Microsoft Office Error Codes