What SMTP Server Error Messages Mean

When configuring email settings using the Specify a Server selection, you may occasionally encounter error messages when attempting to send an email. These messages typically indicate a configuration, connection, or security-related issue and can often be resolved by reviewing a few common settings.

This article explains frequently encountered SMTP server error messages, what they mean and recommended next steps.

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General Troubleshooting Tips

Before reviewing specific error messages, confirm the following basic settings. These steps apply whether you are using standard SMTP authentication or OAuth.

• Ensure the SMTP server address is entered correctly (example: smtp.exampleprovider.com)
• Verify the SMTP port matches the requirements of your email provider (commonly 465 or 587)
• Confirm the Secure Connection option (None, SSL, or TLS) aligns with the selected port
  • Some email providers enforce modern security requirements and may not accept unencrypted connections. If the Secure Connection is set to None, the provider may reject the connection. In these situations, configuring the Secure Connection to SSL or TLS is commonly required, depending on the provider’s security policies.
• If using standard SMTP authentication (Not OAuth), verify the username and password entered are correct
• If using OAuth with Microsoft email accounts, confirm the following fields are populated (rather than username and password):
  • OAuth Client ID
  • OAuth Tenant ID
  • OAuth Client Secret
• Confirm the From email address is populated and valid

If you are unsure which values should be used, or whether changes are appropriate, contact your internal IT team for guidance.

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Common Error Messages and What They Mean

Error connecting or logging into the SMTP server

What this means: The system was unable to connect to your SMTP server or log in successfully.

Common causes:

• Incorrect SMTP server address
• Wrong SMTP port or secure connection setting
• Incorrect credentials or expired OAuth configuration
• Firewall or network restrictions blocking the connection

What to do:

• Double-check the SMTP server name, port, and secure connection settings
• If using OAuth, have your IT team confirm OAuth credentials and permissions
• Verify firewall and network access

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Error logging into server

What this means: A connection to the SMTP server was made, but authentication failed.

Common causes:

• Incorrect username or password (non-OAuth)
• Expired or invalid OAuth Client Secret
• Authentication required but not enabled

What to do:

• Re-enter credentials if using standard SMTP authentication
• For OAuth, have your IT team review Microsoft Azure OAuth configuration

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Blank FROM address

What this means: The email does not have a sender (From) address.

Why this matters: Emails without a From address are frequently rejected or flagged as spam.
What to do:

• Enter a valid email address in the From field
• Ensure the From address is permitted by your SMTP server or Microsoft tenant

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Invalid FROM / TO / CC / BCC address

What this means: One or more email addresses used in the message are not valid.
Common causes:

• Typos or missing characters
• Extra spaces, or formatting issues

What to do:

• Review and correct all email addresses located on either:
  • The Global E-mail Settings 
  
  
  • Edit Portal User screen under:
    • User Info section (the user's e-mail address)
      
      
    • Individual module overrides (if enabled on Global E-mail Settings)

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Error messages mentioning the body or envelope

What this means: The SMTP server reviewed the message and rejected it because of how the email was structured or what it contained

Common causes:

• Invalid or broken formatting, such as malformed HTML or missing message details 
• Extra line breaks, special characters, or content pasted from another program
• Message formatting the receiving email system (SMTP server) can’t process

What to do:

• Review the email content for formatting issues
• Confirm SMTP security and content filtering settings

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Unable to relay

What this means: Your SMTP server does not allow this system to send emails on its behalf.

What to do:

• If you are using relay on the SMTP server, ensure the following IP addresses are included in your list of allowed relay client:
  • Primary: 198.147.32.158
  • Secondary: 198.147.34.158
• If applicable, also review your server’s spam or security filtering service to confirm it is not blocking relay traffic.

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EHLO command failed: 220 We do not authorize the use of this system to transport unsolicited, or bulk email

What this means: The SMTP server accepted the connection but rejected the email request because the connection settings do not meet security requirements.

This does not mean you are sending spam. It commonly indicates a mismatch between the SMTP port and secure connection type, or insufficient trust for the connecting system.

What to do:

• Review the SMTP Port and Secure Connection settings
• Confirm required encryption, relay permissions, or OAuth configuration with your IT team

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When to Contact Your IT Team

If errors continue after reviewing these settings, contact your internal IT team to:

• Confirm SMTP or Microsoft OAuth configuration
• Validate security, relay, and firewall rules
• Review Microsoft Azure OAuth permissions and credential expiration

Providing the exact error message will help speed up troubleshooting.