To prevent spam from being delivered directly to your server, we strongly recommend that you allow incoming mail traffic only from our IP address ranges:

Range: 83.246.65.0/24 with subnet mask 255.255.255.0, corresponds to 83.246.65.0 to 83.246.65.255
Range: 94.100.128.0/20 with subnet mask 255.255.240.0, corresponds to 94.100.128.0 to 94.100.143.255
Range: 185.140.204.0/22 with subnet mask 255.255.252.0, corresponds to 185.140.204.0 to 185.140.207.255