Not overly annoying, secureserver.net is a regular content spammer on my site. I thought it would be good to track them down. Their host names lookup properly and they seem to ban properly, so there seems to not be anything tricky or suspicious.
Observations:
n1plcpnl0063.prod.ams1.secureserver.net 46.252.205.189
p3plcpnl0342.prod.phx3.secureserver.net 50.62.161.109
p3nlhg1196.shr.prod.phx3.secureserver.net 50.63.196.77
p3slh164.shr.phx3.secureserver.net 72.167.131.53
p3nlhg189.shr.prod.phx3.secureserver.net 97.74.24.189
smtpout16-01.prod.mesa1.secureserver.net 97.74.104.208
Sg2plpkivs-v03.any.prod.sin2.secureserver.net 97.74.104.222
p3nlwpweb375.prod.phx3.secureserver.net 104.238.120.3
N1nlhg336c1336.shr.prod.ams1.secureserver.net 146.255.36.1
p3plgemwbe11-v01.prod.phx3.secureserver.net 173.201.192
sg2plwbeout19-1.prod.sin2.secureserver.net 182.50.144.34
sg2plcpnl0020.prod.sin2.secureserver.net 182.50.132.87
p3nw8shg390.shr.prod.phx3.secureserver.net 184.168.27.206
a2plcpnl0191.prod.iad2.secureserver.net 198.71.228.16
Research:
198.71.225.127
a2plcpnl0047.prod.iad2.secureserver.net 198.71.225.140
a2plcpnl0054.prod.iad2.secureserver.net 198.71.226.42
a2plcpnl0123.prod.iad2.secureserver.net 198.71.227.48
a2plcpnl0157.prod.iad2.secureserver.net 198.71.228.51
a2plcpnl0226.prod.iad2.secureserver.net 198.71.228.65
a2plcpnl0240.prod.iad2.secureserver.net 198.71.228.73
a2plcpnl0399.prod.iad2.secureserver.net 198.71.231.45
a2plcpnl0365.prod.iad2.secureserver.net