Webform output destination based on user's email address

I know how to make a webform determine who to send its output to based on the user's selection in a "Select Options" field. But what about basing that decision on a text field? For example, we have an internal work request form in which the user needs to provide her email address so we can provide a response. I'd like to check that email address against a short list (say, a department's employee roster) and, if there's a match, send the form output to the user's manager. Is that possible?