Exchange Connection Problems

How to Fix SMTP Port 587 Authentication Errors on Multifunction Printers

Maira Mehtab Sep 22, 2026 869 views

Question details

The user needs to resolve authentication errors preventing a multifunction printer from sending emails via authenticated SMTP on port 587.

Product: Microsoft Exchange
Device & OS: not provided
Scenario: Configuring a multifunction printer to send outgoing emails through an Exchange or Microsoft 365 account using port 587.
Observed behavior: The printer displays unknown username and password errors and fails to authenticate, preventing emails from being sent.

Before you start

Ensure you have the login credentials for the email account being used by the printer and access to the email server's administrative portal.

Solution 1Recommended

Verify Username Format and Sending Permissions

Correctly format the login credentials and ensure the account is authorized to send emails from the designated address.

SMTP authentication often fails because the username is entered in an outdated format or the mailbox lacks the necessary permissions to act as a sender.

Access the Printer's Web Interface

Type the IP address of your multifunction printer into a web browser and log in with administrator credentials to access the network or email settings.

Update the Username Format

Locate the SMTP authentication section and ensure the username is entered in the full email address format (e.g., user@domain.com) rather than just the alias.

Check Send Permissions

Log into your Exchange or Microsoft 365 admin center, locate the mailbox used by the printer, and verify that the account has 'Send As' or 'Send on Behalf' permissions for the configured sender address.

Tip: Using a dedicated licensed mailbox or a properly configured shared mailbox for the printer can prevent permission conflicts.

Solution 2

Enable Authenticated SMTP and Verify TLS

Ensure the email server allows SMTP authentication and the printer is using the required TLS encryption.

Solution 3

Test Connectivity and Check Domain Records

Use diagnostic tools to identify network blocks or domain configuration issues like missing SPF records.

Free Microsoft Office alternative

Looking for a Lightweight and Free Office Suite?

While resolving complex Exchange server and printer networking issues, you might also be looking for ways to streamline your daily office tasks. WPS Office is a highly compatible, free, and lightweight alternative to Microsoft Office. It offers a familiar interface, allowing you to seamlessly transition and manage your documents without expensive subscriptions.

1. Download the Installer: Visit the official WPS Office website and download the free installation package for your operating system.
2. Install WPS Office: Run the downloaded installer and follow the on-screen instructions to set up the software on your device.
3. Open Your Documents: Launch WPS Office to instantly open and edit your existing Microsoft Office files with perfect formatting retention.

Fully compatible with Microsoft Word, Excel, and PowerPoint formats (.docx, .xlsx, .pptx)Lightweight design that runs smoothly even on older PCs and MacsFamiliar and intuitive user interface for a zero-learning-curve migrationBuilt-in PDF reader and editor to effortlessly manage scanned documents from your printer

microsoft office alternative - wps office

Frequently Asked Questions

Why does my multifunction printer require port 587 for SMTP?

Port 587 is the standard port for SMTP message submission. Unlike port 25, which is often used for unauthenticated relaying, port 587 requires authentication and TLS encryption, ensuring that your email credentials and data are transmitted securely.

How do I know if my printer supports TLS encryption?

You can check your printer's web interface under the network or email setup sections. Look for security dropdown menus featuring STARTTLS, SSL, or TLS options. Alternatively, consult the technical specifications in your printer's user manual.

What should I do if my IP address is blacklisted or blocked?

If your IP is blocked from sending emails, you will need to contact your email service provider or IT administrator. For Microsoft 365, administrators can use the Microsoft Defender portal to request delisting of your public IP address from the blocked senders list.

Outlook & Email Problems