Looks like there were quite a few directory harvest attacks around Easter. Perhaps those repsonsible for these directory harvest attacks figured people would have better things to do on the holidays than pay attention to their mail servers.
Begin Time 04/13 23:55:33
End Time 04/13 23:56:47
IP Address 71.68.21.45
Road Runner HoldCo LLC
Begin Time 04/12 20:11:27
End Time 04/12 20:12:59
IP Address 206.252.161.165
Earthlink, Inc.
Begin Time 04/12 15:57:26
End Time 04/12 15:58:59
IP Address 69.171.162.121
Cricket Communications Inc
Begin Time 04/12 12:53:01
End Time 04/12 12:54:39
IP Address 71.188.170.110
Verizon Internet Services Inc.
Begin Time 04/12 09:44:12
End Time 04/12 09:45:51
IP Address 72.14.74.9
ISP Alliance, INC. / Sjoberg Cable MNCABLE