You could do this, but you'd have to modify the routing tables to make sure packets destined for one set of IP addresses (for email) go over the first VPN connection, and packets destined for the other set of IP addresses (for the application) go over the second VPN connection. It's a pain to make work, and you have to do it every time you connect your VPN sessions (or make it static, which could cause other issues when the VPN connections are not established). Your better option is to publish one (or both) applications to the public internet, if possible, so that VPN connections are not required to use this (especially if your email is Exchange 200x / Outlook 200x, as you can use RPC over HTTP or publish the RPC via an ISA 2004/2006 firewall).