I've tried searching for this topic on the forums and the web and couldn't find a conclusive answer. Maybe some of you veterans here can shed some light on this question [:)]
With those services, the anti-spam is already good, so there's really no reason. Gmail uses SSL which is not supported by the POP3 Proxy. I don't know about Yahoo and Hotmail.
Cheers - Bob
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005