Difference between the Active Directory Custom Class attribute Email Address and the Proxy Address attribute

Question

I use the Proxy-Address attribute as the main way to determine the user's email address (where I only care about addresses with the prefix "SMTP:" or "smtp:" and, in addition, I use the address with the prefix with uppercase SMTP - this is not 100% more reliable, but this is a limitation of the existing system).

I was informed that this attribute (Ldap-Display-Name = mail, CN = E-mail-Addresses) can be used as a rollback to determine the user's email addresses (if no smtp addresses can be found in the Proxy Address Attribute) , but I can’t find examples of multiple addresses for this attribute.

The MSDN documentation indicates that the E-mail-Address attribute should be "the list of email addresses for a contact" . In all the examples that I find, there is only one address, and it does not have a prefix with "SMTP:" or "smtp:", so I'm not sure how to determine the primary email address, unless the reality is that the mail attribute should only ever one address?

Answer 1

You can find the following useful ones from http://blogs.technet.com/b/exchange/archive/2005/01/10/350132.aspx

Email Attributes

Exchange stores and uses recipient email address information in the following attributes: proxyAddresses

This is the primary attribute that stores information about email addresses. When you open recipient properties in Outlook and look at the E-mail Addresses tab, you are viewing this attribute. This is a multi-valued string containing all addresses representing the recipient. Each value should have the following format:

  type:address 

For instance:

  SMTP: [e-mail] 

If the type is written in capital letters, the address is considered the primary address of this type and is used as the default answer for the address of this recipient. If the type is lowercase, the address is considered a secondary address and is used to resolve addresses during delivery by email, allowing the same recipient to receive emails directed to different email addresses.