Send & Receive Issues

How to Fix SMTP Authentication Errors When Sending Email from a Scanner

Olivia Miller Sep 27, 2026 870 views

Question details

The user needs to resolve SMTP authentication failures when attempting to send scanned documents via email directly from a scanner or multifunction printer.

Fix SMTP Authentication Errors When Sending Email from a Scanner

Product: Microsoft 365 / Exchange Online
Device & OS: not provided
Scenario: Configuring a multifunction printer or scanner to send scanned documents via email through Microsoft 365 servers.
Observed behavior: The scanner fails to send emails due to incorrect SMTP server settings, unsupported authentication methods, wrong port numbers, or missing security configurations.

Before you start

Ensure you have administrator access to your Microsoft 365 admin center and the IP address or web interface login credentials for your multifunction scanner.

Solution 1Recommended

Configure SMTP AUTH Client Submission

Use this method if your scanner supports logging in with a Microsoft 365 mailbox username and password, allowing you to send to both internal and external recipients.

SMTP AUTH client submission is the most common method for scanners to send email. It requires the device to authenticate directly with Microsoft 365 using a valid email account.

Access scanner settings

Enter SMTP server details

Set the SMTP server address to 'smtp.office365.com'. Change the port to 587 (recommended) or 25, and enable TLS/STARTTLS encryption.

Configure authentication

Enter your Microsoft 365 email address as the login username. Provide the password for the account.

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

Solution 2

Set Up Microsoft 365 Direct Send

Ideal if your scanner cannot use SMTP AUTH but only needs to send emails to internal recipients within your own Microsoft 365 organization.

Solution 3

Configure a Microsoft 365 SMTP Relay

Best for organizations needing to send emails to external addresses without device-level authentication, utilizing a static public IP address.

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Frequently Asked Questions

Why is my scanner failing to authenticate with Microsoft 365 using my correct password?

Authentication often fails because Multi-Factor Authentication (MFA) or Security Defaults are enabled on the sending account. Since scanners cannot handle MFA prompts, you must generate an 'App Password' in your Microsoft 365 security settings and use it in the scanner's password field instead of your regular password.

What port should I use for SMTP AUTH client submission?

Microsoft highly recommends using Port 587 for SMTP AUTH client submission along with TLS/STARTTLS encryption enabled. Port 25 can also be used, but it is frequently blocked by local ISPs and network firewalls to prevent spam.

Can I send emails to external addresses using the Direct Send method?

No, Direct Send only allows you to send emails to recipients within your own Microsoft 365 organization's domains. If you need to send scanned documents to external clients or vendors, you must use SMTP AUTH client submission or configure an authenticated SMTP relay.

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