Getting Gmail IMAP #993 and Gmail SMTP #587 thru firewall set at "Maximum Security [High]"

Hello,

With the Actiontec router's firewall set at "Typical Security [Medium], Outlook 2010 can send/receive mail. However when the firewall is set to "Maximum Security [High]" mail transport fails. This is due, I understand to, the firewall blocking the non-standard assignments of IMAP to port 993 and SMTP to port 587, for the sake of encrypted mail transmission.

I would like to know if there is a way of retaining the maximum firewall setting whille allowing Gmail traffic through, perhaps port forwarding or some othe mechanism. How would this be set up. Clear details, Please.

Thank you