Hi>
I have routerboard with 2 internets on.
Its all ok and routing for incomming nat, but what I am trying to do is setup a route where certain ports use a specific internet outgoing.

Hopefully that makes sense.

You mean, i.e. in case of HTTP(S) select WAN1 and SMTP select WAN2?

yes I guess so. In fact I am using port 5001, which I want to go out on the the router plugged into port 4 of the microtik.