To Reject Mail From a Specific Network
Note: If you want to score mail higher from a specific organization which may have multiple subnets you should use their ASN instead. See here for more information.
- Navigate to Warden -> Settings -> Mail Server Access -> Client Access.
- Click the Add button on the grid and add the CIDR as the pattern with the action set to REJECT - Reject the request.
- Press the Submit button to add the CIDR. Rejected servers will be listed under the Warden -> Logs -> Reject log.

Refer to the CIDR Subnet Table to find the CIDR equivalent of a decimal subnet mask.
IPv4
| CIDR Prefix | Total IP Addresses | Network Mask |
| /8 | 16,777,216 | 255.0.0.0 |
| /16 | 65,536 | 255.255.0.0 |
| /24 | 256 | 255.255.255.0 |
| /25 | 128 | 255.255.255.128 |
| /26 | 64 | 255.255.255.192 |
| /27 | 32 | 255.255.255.224 |
| /28 | 16 | 255.255.255.240 |
| /29 | 8 | 255.255.255.248 |
| /30 | 4 | 255.255.255.252 |
| /31 | 2 | 255.255.255.254 |
| /32 | 1 | 255.255.255.255 |
IPv6
| CIDR Prefix | Total IP Addresses |
| /64 | 18,446,744,073,709,551,616 |
| /56 | 256 /64 subnets |
| /48 | 65,536 /64 subnets |