We are installing a SonicWALL TZ190 Enhanced firewall to replace a Cisco PIX 615. The domain has a Exchange 5.5 server that currently hosts the mail but also uses a spam filtering email service. We can send mail out using the Outlook client but cannot receive mail. Port 25, 143, 135, and 110 have all been opened and forwarded traffic to Exchange server. The outgoing mail goes directly through the Exchange server but the incoming mail goes to the spam service first then to the server. The instructions from the spam service was to open a range of IP's and that has been done but we still seem to not be able to receive. Any suggestions?