How do I Restrict Direct Delivery of Spam?
To prevent spammers from delivering spam directly to your mail servers without filtering, you must make sure your mail server only accepts emails originating from the Spam Experts filtering system.
To only accept messages from your filtering nodes you need to allow emails based on your delivery hostname(s) or IP(s). For ease of use, we recommend that you create a delivery hostname in the DNS of all your filtering node IPs. For Spam Experts Hosted Cloud, the hostname is: delivery.antispamcloud.com (Note - IP addresses may change, therefore only hostname-based Allow listing is supported).
Alternatively, if allowing emails based on hostname is not an option, you could change your destination mail server to listen on an alternative one, such as port 2525 instead of the default 25 . The special port can be set for delivery when editing the destination route for your domain.
Please make sure your firewall does not block DNS port 53 TCP (to avoid hitting the UDP packet limit size).
Delivery Restriction Examples
The following describe how to configure your MTA to restrict filtering to the
- Configure Incoming Filtering with Exchange Online (Microsoft 365)
- Configuring Outgoing Filtering with Exchange Online (Microsoft 365)
- Exchange 2003 Configuration
- Exchange 2016-2019 Configuration
- Configure Filtering With Google Workspace
- Configuring Exim with cPanel and WHM for Spam Experts mail routing
- Configure Incoming Filtering with Postfix
- SmarterMail Configuration (Windows 2012)
- Exim - Direct Admin Configuration
- Qmail Configuration
- Cisco IOS Based Router Configuration
- Cisco ASA Based Device Configuration
For any other MTA configuration details, please consult the relevant MTA documentation.
Allow incoming delivery from the IP range 18.104.22.168/22 and securemail.management.