I want to delegate my Google Apps email to someone else's Gmail.

I toggled the delegation flag in the Admin Console. 

I then clicked on "Grant access to your account" in my Settings and entered their email, but got the following error:

> Error: You can only grant access to Google accounts in the same Google Apps organization.

Is it possible to delegate to domains outside of my organization? (I read somewhere about doing a MX verification, but we've already done that.)