dict_of_emails = {'1': 'someone@gmail.com', '2': 'someone@yahoo.com', '3': 'someone@hotmail.com'} # Jeez, hotmail, IKR!


key = 1   # Recieved by the system from another file, value maybe 2, maybe 3

print dict_of_emails[str(key)]  # Need to get an email ID out of this