Do you know that Blackberry uses their own BIS servers to provide email facility to blackberry mobile users ?
Yes, When you access any email server from you BlackBerry mobile, The request is originating from the Blackberry BIS server IP, and not from your Public IP.
So, To provide proper communication between the BlackBerry Internet Service and the BlackBerry smartphone users email messaging environment, the Mail Service Provider must allow traffic from the following Internet Protocol (IP) ranges to ensure proper communication with the BlackBerry Infrastructure.
The IP rage is available [on this BlackBerry KB Link](http://btsc.webapps.blackberry.com/btsc/viewdocument.do?noCount=true&externalId=KB11036&sliceId=2&dialogID=63832630&cmd=displayKC&docType=kc&stateId=1+0+63826436&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl)
At the time of this writing, The following IPs are available on the link.
| IP Address | NetMask | CIDR Notation | Range | |
| Start | End | |||
| 206.51.26.0 | 255.255.255.0 | 206.51.26.0/24 | 206.51.26.0 | 206.51.26.255 |
| 193.109.81.0 | 255.255.255.0 | 193.109.81.0/24 | 193.109.81.0 | 193.109.81.255 |
| 204.187.87.0 | 255.255.255.0 | 204.187.87.0/24 | 204.187.87.0 | 204.187.87 .255 |
| 206.53.144.0 | 255.255.240.0 | 206.53.144.0/20 | 206.53.144.0 | 206.53.159.255 |
| 216.9.240.0 | 255.255.240.0 | 216.9.240.0/20 | 216.9.240.0 | 216.9.255.255 |
| 67.223.64.0 | 255.255.224.0 | 67.223.64.0/19 | 67.223.64.0 | 67.223.95.255 |
| 93.186.16.0 | 255.255.240.0 | 93.186.16.0/20 | 93.186.16.0 | 93.186.31.255 |
| 68.171.224.0 | 255.255.224.0 | 68.171.224.0/19 | 68.171.224.0 | 68.171.255.255 |
| 74.82.64.0 | 255.255.224.0 | 74.82.64.0/19 | 74.82.64.0 | 74.82.95.255 |
| 173.247.32.0 | 255.255.224.0 | 173.247.32.0/19 | 173.247.32.0 | 173.247.63.255 |
| 178.239.80.0 | 255.255.240.0 | 178.239.80.0/20 | 178.239.80.0 | 178.239.95.255 |
| 180.149.148.0 | 255.255.252.0 | 180.149.148.0/22 | 180.149.148.0 | 180.149.151.255 |
| 180.168.204.0 | 255.255.252.0 | 180.168.204.0/22 | 180.168.204.0 | 180.168.207.255 |
| 5.100.168.0 | 255.255.248.0 | 5.100.168.0/21 | 5.100.168.0 | 5.100.175.255 |
| 131.117.168.0 | 255.255.248.0 | 131.117.168.0/21 | 131.117.168.0 | 131.117.175.255 |
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