Hi
I am using routeros5.17
I have successfully setup and connected to an openvpn server on mikrotik via a windows client. I get my virtual ip upon connection (10.0.0.2) however I am not able to connect to other computers on the network via the VPN (DHCP 192.168.0.100-200). For example I want to connect to the mail server to get my emails and also to another file server on the same network using samba shares.
Please advise how this is possible. 
Your VPN clients need to know how to reach your network (192.168.0.0 255.255.255.0 I presume). On a linux (or windows) ovpn server, you push routes to your clients. This is not possible on a mikrotik, so you will have to add a route towards your VPN gateway yourself on your client machine.
Another way is to make an ethernet based OpenVPN network (tap) and let your mikrotik router handle the DHCP (in stead of ovpn, by putting the ovpn interface and the lan interface(s) as a bridge port). Your ovpn clients can then be in the same subnet, so no additional routing configuration is needed. This type of tunnel does tend to generate more overhead, since more traffic is generated (usually), but nothing a mikrotik can’t handle 
.