Hi Atawalpa ! You either have to allow POP3 (port 110) service from your internal network to your mail server or you have to enable the "POP3 proxy" !!! - Good luck - kind regards, erich
If you have a catchall filter rule in place to allow general access from your Internal network to the outside world, then mail access should not be a problem. The following filter rule does the trick:
Internal_Network Any Any Allow
If you are using more restrictive filter rules, then you are preventing the machines on your Internal network to access services in the outside world that you have not explicitly allowed for in your packet filtering rules.