If you’re integrating with the iPaper servers, you should expect requests from the following IP ranges:

92.62.194.32/28     (92.62.194.32 - 92.62.194.47)
217.195.177.1/30    (217.195.177.1 - 217.195.177.2)
79.125.0.0/17       (79.125.0.0 - 79.125.127.255)
46.51.128.0/18      (46.51.128.0 - 46.51.191.255)
46.51.192.0/20      (46.51.192.0 - 46.51.207.255)
46.137.0.0/17       (46.137.0.0 - 46.137.127.255)
46.137.128.0/18     (46.137.128.0 - 46.137.191.255)
176.34.128.0/17     (176.34.128.0 - 176.34.255.255)
176.34.64.0/18      (176.34.64.0 - 176.34.127.255)
54.247.0.0/16       (54.247.0.0 - 54.247.255.255)
54.246.0.0/16       (54.246.0.0 - 54.246.255.255)
54.228.0.0/16       (54.228.0.0 - 54.228.255.255)
54.216.0.0/15       (54.216.0.0 - 54.217.255.255)
54.229.0.0/16       (54.229.0.0 - 54.229.255.255)
54.220.0.0/16       (54.220.0.0 - 54.220.255.255)
54.194.0.0/15       (54.194.0.0 - 54.195.255.255)
54.72.0.0/14        (54.72.0.0 - 54.75.255.255)
54.76.0.0/15        (54.76.0.0 - 54.77.255.255)
54.78.0.0/16        (54.78.0.0 - 54.78.255.255)
54.74.0.0/15        (54.74.0.0 - 54.75.255.255)
185.48.120.0/22     (185.48.120.0 - 185.48.123.255)
54.170.0.0/15       (54.170.0.0 - 54.171.255.255)
54.154.0.0/15       (54.154.0.0 - 54.155.255.255)