Exhange and POP3/SMTP

I am running Exchange 5.5 SP4 located behind my firewall, I am using a SMTP relay server to relay and filter outbound and inbound email from the internet. I have a user that is located at a remote location with only access to the internet and I need to set him up to access our exchange server. He doesn’t like using OWA. I don’t want to open any unnecessary holes in my network to allow him access via POP3. Does anyone have any suggestions on what I can do?