My residential ISP connection does not allow port 25 traffic in or out, i have a PPTP tunnel from my residence to my Office
My office ISP allows port 25 traffic to pass through.
How can i create a rule that will divert outgoing port 25 traffic from my residence through the VPN out to the internet ?
you need to create a mangle rule to mark connections to port 25.
Then, you need to apply a routing mark to this connections and add route which will route the so marked connections over your VPN tunnel.