If you work with more than one agency that uses the Atrium Mobile application, with version 2.1.11 you no longer need to have a unique email address for logging in to each of them on you mobile device.  You need to put your email address in and click the green checkbox and you will see one of these two screens:

If you have entered a valid email address, simply put your password in the blank box.  Only if you are presented with a dropdown box, you will need to select with which company you want to connect and then click 'Login'.  Otherwise, just click 'Login'