Ports your SpamDuster server listens on
| Port | Used for |
|---|---|
| 25 | Incoming mail from the internet. |
| 443 | The console, over HTTPS. |
| 80 | Issuing and renewing the server's certificate, and redirecting to HTTPS. |
SpamDuster Cloud does not accept mail submission from users' mail programs. It filters incoming mail only.
What your mail server must allow
Allow incoming connections from your SpamDuster server's IP address to your mail server, on the port you set as the Destination mail server port, usually 25. If your mail server limits, greylists or checks the reputation of connecting servers, exempt the SpamDuster server's IP address.
Find your SpamDuster server's IP address
Look up the address of your Mail host (MX target), the hostname in your welcome email. On a computer with a terminal:
nslookup 123456.customer.spamduster.com
Replace the example with your own hostname.
Hostnames
| Name | What it is |
|---|---|
| Your Mail host (MX target) | Your server's hostname, for example 123456.customer.spamduster.com. Your MX records point at it, and your console is at https:// followed by it. |
| Your custom hostname, if you set one | A name on your own domain that also points at your server. See Use your own hostname for the filter. |
Updated 2026-10-26Need help? Open a ticket in the billing portal.