Outlook from the outside are you crazy A

Okay so my users don’t like my VPN solution, despite the fact that they knew about it months before the Exchange server they are complaining. The laptop users say that Outlook is too slow or that it takes too long to synchronize. Blah, Blah, Blah, most are saying that they would rather be on POP, ackkkk. I can’t let that happen. Any ideas on how to ease their pain? How ridiculous would it be to open the ports for Outlook to work on the firewall, what are the ports, what are the exploits for such a horrible idea.