How to use two email hosts?

A client wants to use Google Apps for employees but they want to offer email accounts to users of their site for which I'm going to use Rackspace email. Rackspace is the cheapest I've found (2/month) that still offers api access even if you only have a few accounts so that's why I'm using them but for employees they want some of the Google features and their free up to 50 employees.

Is there anyway to handle this at the mx record level or do I need to do some开发者_运维百科 forwarding?

It is not possible to direct email messages sent to the same domain to two different mail servers using MX records.

You need to do forwarding.