Clarify: You want to show mail address instead of display name in the “To”, “From” and “CC” fields

Explanation: When messages arrive to exchange, server will resolve the mail address to those users who exist in the directory, there isn’t a way to change the behavior which is expected by design

Workaround (For Exchange 2003):

Notes: Not recommend [See KB 828770], it also causes all messages through modified SMTP Virtual Server to show mail address instead of display name

  1. Start Registry Editor [Set on server which your mailbox stays]
  2. Locate or create the following key in the registry
    Notes: You might need to create the ”Parameters” key and the <2> key as well, <2> is the SMTP virtual server number
  3. Add the following registry value: Name: ResolveP2 Type: REG_DWORD Value: 0
  4. Also enable ”allow anonymous senders” on the SMTP Virtual Server
    a.  ESM->AG->Server->ServerName->Protocols->SMTP->SMTPVirtualServerName’s Properties
    b. “Access” tab->”Authentication” button->check “allow anonymous senders”

Notes: For Exchange Server 2007, name resolution is forced for MAPI clients, no way to disable

Here’s a 3rd-party tool which can achieve the function you want: WhichAddress