We validate the Primary Admin address but we do not validate employee or secondary admin addresses.
We use e-mail addresses as the connection user name for convenience. We do not validate the employee address, however, we ask that you create an alias on your email system that forwards to a real person so that we don't get bounces. This allows you to use real emails for field employees, but also use some place holder email addresses such as warehouse@abc.com or office@abc.com as needed for secondary admins.