Return URL link from outside domain

I am trying to setup some links inside of our email that ha​ve a ReturnURL value. For these links we want the user to be taken to specific pages inside of our customer site instead of the default customer site homepage. Here is an example of one of the links I setup www.mydomain.com/login. From what I read in the documentation this should send the user to our system details page once the user logs in.

Am I doing something incorrect with these links? Do return URL links work from outside domains such as emails? I am at a loss as to why these links are not working. Any help[ would be appreciated. 

Thanks.

I solved this issue on my own by accident. The issue was I need to use ?returl= instead of ?ReturnUrl=