I am unclear on what you are describing but it appears to be associated with addressbook aliases so I will talk about that for now.
In addressbooks, the "name" value can be an alias that resolves to its associated email address. That is an option that must be enabled, either globally or per addressbook. Configuration is done via the "Addressbook properties" settings that can be accessed using the "Book" button located in the toolbar of the "Addressbooks and distribution lists" window.
When the option to "Apply the e-mail address instead of the alias" is enabled, then you can enter an addressbook "name" in the To: field of a new message and its associated "e-mail address" will be used when the message is sent. Otherwise, entering an addressbook "name" in the To: field will result in an invalid email address error.
I am unclear on what you are describing but it appears to be associated with addressbook aliases so I will talk about that for now.
In addressbooks, the "name" value can be an alias that resolves to its associated email address. That is an option that must be enabled, either globally or per addressbook. Configuration is done via the "Addressbook properties" settings that can be accessed using the "Book" button located in the toolbar of the "Addressbooks and distribution lists" window.
When the option to "Apply the e-mail address instead of the alias" is enabled, then you can enter an addressbook "name" in the To: field of a new message and its associated "e-mail address" will be used when the message is sent. Otherwise, entering an addressbook "name" in the To: field will result in an invalid email address error.