title: Difference between the Active Directory User class' E-mail-Addresses attribute vs. the Proxy-Address attribute
body: <p>I am using the Proxy-Address attribute as a primary means of determining the user's email address (where I only care about the addresses prefixed with "SMTP:" or "smtp:" and, furthermore, I am using the address prefixed with an uppercase SMTP to determine the primary address - this is not 100% reliable, but it's a limitation of an existing system).</p>
  
  <p>I was informed that this attribute (Ldap-Display-Name = mail, CN = E-mail-Addresses) can be used as a fall back, to determine a user's email addresses (if no smtp addresses can be found under the Proxy-Address attribute(s)), but I can't find examples of multiple addresses for this attribute. </p>
  
  <p>The MSDN documentation indicates that the E-mail-Address attribute should be <code>"the list of email addresses for a contact"</code>. In all the examples I am finding, there is only a single address and it is not prefixed with "SMTP:" or "smtp:" so I am unsure how one would determine the primary email address unless the reality is that the mail attribute should only ever be a single address?</p>