How to forward email to external email addresses, like gmail, hotmail

I've Exchange 2013, and for user bob@mydomain.com, i want to forward email to his hotmail address: bob@hotmail.com

I created a contact for bob@hotmail.com>
i edit the properties of bob@mydomain.com, to mailbox feature, MailFlow->Delivery Options, i check the tab to forward email, to contact for bob@hotmail.com, but it could not be shown

How can i do this???

REgards!

Lasandro Lopez