• SonicOS 7.1
• About SonicOS
  • Working with SonicOS
  • SonicOS Workflow
  • How to Use the SonicOS Administration Guides
  • Guide Conventions
• Anti-Spam
  • About Anti-Spam
    • What is Anti-Spam?
    • Benefits
  • How Does the Anti-Spam Service Work?
    • GRID Network
      • Benefits
      • GRID Connection Management with Sender IP Reputation and Connection Management Precedence Order
    • Address and Service Objects
      • Objects Created When the Anti-Spam Service is Enabled
  • Purchasing an Anti-Spam License
• Status
• Settings
  • Activating Anti-Spam
  • Installing the Junk Store
  • Configuring Email Threat Categories
  • Configuring Access Lists
    • Configuring User-defined Access Lists
    • Adding a Host to the Access Lists
  • Configuring Advanced Settings
• Relay Domains
  • About Open Relay
  • Listing Allowed Relay Domains
• Junk Box Messages
  • Information Displayed in the Junk Box Messages Table
  • Managing Junk Box Messages
• Junk Box Settings
• Junk Box Summary
  • Managing the Junk Box Summary
• User View Setup
  • Configuring User View Setup
• Address Books
  • About the Tabs
    • Allowed Lists
    • Blocked Lists
  • Adding Items to the Allowed or Blocked List
  • Deleting Items from the Allowed or Blocked List
  • Importing Address Book Entries
  • Exporting Address Book Entries
  • Searching the Allowed and Blocked Lists
• Manage Users
  • Updating the User Table
  • Enabling Non-LDAP User Authentication
  • Viewing Users
    • Selecting the Type of User to View
    • Selecting a Server’s Users to View
    • Finding a User
  • Adding Users
    • Adding Users Manually to the User Table
    • Importing Users to the User Table
  • Signing In as a User
• LDAP Configuration
  • Adding an LDAP Server
    • Configuring LDAP Queries
    • Adding LDAP Mappings
  • Editing an LDAP Server Configuration
  • Deleting an LDAP Server
• Advanced
  • Downloading System/Log Files
  • Selecting Log Settings
• Downloads
• SonicWall Support
  • About This Document

About Open Relay

An open relay is a SMTP server configured in such a way that it allows a third party to relay (send/receive email messages) that are neither from nor for local users. Such servers, therefore, are usually targets for spammers.

When CASS is configured as an open relay, the mail is relayed even if the mail is not destined to the recipient domain. When CASS is not configured as an open relay, it relays the emails that have one of the listed recipient domains; for domains not listed, the mails are rejected. Listing allowed relay domains avoid unnecessary relaying of emails even when mails are not destined to the user.