I've setup an RBLDNS lookup at Docunext, here are some examples:
78.88.191.111
87.117.8.182
91.124.17.189
189.18.215.72
200.100.159.80
200.207.67.247
201.35.233.53
201.43.67.218
201.88.36.34
201.143.189.168
213.202.131.53
217.217.141.100
217.198.149.150
77.200.164.231
78.25.50.226
90.213.168.205
74.60.194.83
79.140.1.74
81.208.13.171
81.67.22.199
190.21.100.83
84.122.95.113
86.63.81.124
87.119.255.157
87.205.138.187
87.253.6.152
93.81.100.195
80.95.77.101
110.37.77.178
213.6.241.90
94.70.30.222
67.173.85.117
94.255.128.186
201.233.245.101
87.206.113.195
212.89.25.223
86.16.171.136
81.106.84.25
71.76.130.13
208.53.12.37
90.141.62.182
83.23.65.169
88.71.27.37
83.21.13.29
61.247.40.250
79.26.104.11
82.63.209.114
79.23.147.153
82.60.17.240
87.208.89.246
87.212.165.44
89.254.203.102
66.152.179.108
143.248.68.59
207.182.253.102
207.182.253.104
207.182.253.106
200.83.151.215
201.241.211.96
124.120.120.75
124.121.38.145
79.166.228.112
92.100.93.226
94.29.14.79
174.137.178.222
68.162.253.19
113.22.110.22
114.200.172.20
114.207.120.42
115.73.174.148
116.46.137.109
121.179.71.149
123.16.131.228
123.22.105.79
123.24.147.254
125.189.156.94
163.180.57.184
166.238.50.66
170.51.95.232
186.58.132.178
186.81.25.128
186.9.167.250
187.40.57.66
189.106.12.215
189.179.101.239
189.73.63.110
189.83.110.107
190.10.3.166
190.103.44.13
190.144.89.198
190.188.139.177
190.209.83.190
190.220.50.144
190.246.22.134
190.49.7.163
190.51.189.20
190.65.96.242
190.67.213.179
190.69.234.139
190.71.6.74
190.96.131.33
190.97.143.17
195.178.153.2
201.17.66.104
201.19.13.173
201.234.254.127
201.29.183.129
202.168.229.166
211.227.78.148
211.47.90.89
213.226.192.126
218.235.169.84
220.92.6.22
41.129.1.233
59.95.15.120
64.234.115.104
67.204.61.146
69.169.197.28
69.28.56.91
71.181.47.13
77.120.64.182
77.126.71.20
77.70.78.82
78.138.168.186
78.163.170.64
78.170.224.245
78.90.242.139
78.96.118.187
79.107.104.237
82.141.138.194
83.228.84.102
84.254.237.228
85.132.29.134
88.235.245.150
88.246.32.222
88.253.128.229
89.123.25.241
89.165.12.113
89.39.55.130
92.46.19.78
92.82.199.180
92.84.92.66
92.85.113.84
93.100.134.212
94.123.119.117
94.123.129.137
94.158.186.33
95.133.151.214
95.134.197.117
95.66.49.232
95.78.138.244
95.78.85.21