Brute force from these IP Addresses...

I'm under a barrage of brute force SMTP auth attempts from these IPs. Is there anything I should do about it besides just add them to the blacklist?

51.75.255.69

193.169.254.67

185.211.245.195

185.234.217.221

45.125.66.37

45.125.66.184

45.125.66.191

45.125.66.193

45.125.66.161

45.125.66.83

45.125.66.133

45.125.66.62