Spam Contribution by IPI briefly reviewed my corpus of 4569 comment spams in my Akismet queue. Of them over 53% of the spam has been contributed by Top 100 spamming IP addresses.

Here is the list of top 100 IP addresses of spammers:

212.0.138.30
83.149.74.179
66.186.173.166
209.128.101.244
210.93.13.77
203.115.1.134
82.160.4.68
213.237.161.9
69.45.68.245
217.219.128.69
195.175.37.71
125.243.207.130
61.5.146.74
61.219.84.212
201.0.4.148
218.188.0.178
61.19.242.37
195.175.37.70
125.244.22.130
195.13.59.228
125.246.186.66
125.247.129.130
202.82.19.173
70.60.165.154
83.138.56.246
65.66.55.12
62.2.219.18
63.219.4.74
69.19.14.12
82.234.138.4
70.88.104.170
125.245.203.22
200.237.79.194
82.127.20.220
217.219.224.69
59.120.112.141
125.240.200.194
219.93.174.105
84.204.232.115
200.76.36.195
80.255.63.30
200.65.127.163
140.127.139.248
213.149.96.214
125.246.109.67
196.200.181.3
85.18.252.145
80.53.207.66
200.122.153.34
125.244.125.131
200.225.194.49
217.219.221.5
62.111.171.159
202.175.58.10
125.241.53.228
43.253.80.135
195.39.134.26
208.50.69.80
212.52.139.94
66.192.30.22
82.138.62.154
80.76.63.72
222.228.173.153
201.209.249.45
208.34.72.8
193.220.51.5
62.50.80.2
132.248.103.131
196.32.134.38
200.188.219.164
61.108.37.2
199.104.191.20
200.55.42.230
201.28.15.226
66.160.176.201
68.109.225.171
200.32.72.202
69.65.134.7
222.151.204.242
203.133.33.170
202.69.192.50
195.77.157.10
200.237.79.193
125.243.145.2
196.40.31.234
210.212.254.2
200.122.153.10
125.245.19.253
200.250.84.155
220.110.189.242
195.39.170.102
83.16.148.52
203.169.251.29
200.65.0.27
61.155.112.174
202.88.129.254
205.160.32.38
210.124.165.54
200.149.78.243
125.246.213.195

Feel free to add them to your IP filter / block list.

It indicates that, even with today's distributed spamming attacks, IP blocking is still an effective means of blocking comment spamming.