it depends on your topology and routing table.
If to reach the destination for the 'outbound mail' (I reall don't know what this is) the next hop is a device in vlan2, the traffic will have to cross the LDIR.
If it is a device on vlan3 and this device does not need to forward the traffic accross the LDIR, then traffic will not go through this box.
This is just a question of routing/switching.
Once you know where you want to go, just follow the path and see if you cross the LDIR.
Gilles.