I have an exchange 2003 server and a SonicWall NSA 3500. I am trying to make iPhones on my network continue to send and receive e-mails when I enable a Brracuda spam filter 300. I had enabled the spam filter, but the iphones stopped sending and receiving e-mails. However, outlook on computers were doing fine and my BlackBerry phone had no problems sending or receiving e-mails. The spam filter has a private IP address, but it was able to filter e-mails before they reach my exchange server. I made sure that only port 25 is forwarded to the spam filter.