Routing to one particular address using IPSec

Hello,

I have following scenario:

HQ FortiGate 91E Active-Passive Cluster with ISP A on WAN 1 with static public IP (via PPPoE) Firmware: 5.4.4 internal IP-Range: 192.168.0.0/24

Branch Single FortiGate 51E with ISP B on WAN 1 with static public IP (via PPPoE) Firmware: 5.4.4 internal IP-Range: IP 192.168.2.0/24

Between the two Branches an IPSec VPN is established.

Now the challenge: From HQ we’d like to reach certain services which are only accessible via ISP B (Port 25, 110, and 80)

Because of the better internet connectivity at HQ with ISP A we try to avoid a whole routing (all traffic) from HQ to branch. So only one particular IP-Address from ISP B should be routed to HQ trough the IPSec – Tunnel to HQ.

Thanks for any ideas and advice.