All spam comes from some where. If you have access to the servers logs you can identify exactly where. If you do not I can set you up so that you do. The phrase, “Knowing is half the battle”, rings true here.
Of the many subnets below 3 are from the US. I can get more into US business spam – which isn’t “opposed” by the spam-can act. Regardless – it is unsolicited and I feel no shame in sharing the information with the public.
The below networks are very broad. But I can assure you blocking mail from them will only help your situation. If you would like details on each network and why let me know.
| 75.102.0.0/255.255.192.0 |
| 72.30.0.0/255.255.0.0 |
| 111.93.0.0/255.255.0.0 |
| 114.200.0.0/255.248.0.0 |
| 117.192.0.0/255.192.0.0 |
| 122.136.0.0/255.248.0.0 |
| 189.192.0.0/255.248.0.0 |
| 58.148.0.0/255.252.0.0 |
| 59.0.0.0/255.224.0.0 |
| 64.12.0.0/255.255.0.0 |
| 77.54.0.0/255.255.0.0 |