OLEXP: Cannot Specify Secondary Sort Key in Outlook Express

You cannot specify the secondary sort key by which your mail messages are displayed in Outlook Express.

The behavior occurs because the secondary sort key by which your mail messages are displayed is determined by the mail protocol Outlook Express is currently using.

This behavior is by design.

You can specify the primary sort key by which your mail messages are displayed by clicking Sort By on the View menu, and then clicking the sort key you want to use. The secondary sort key is determined by the mail protocol Outlook Express is currently using. For example, the Post Office Protocol 3 (POP3) protocol uses the Received column as the secondary sort key, and the Internet Mail Access Protocol 4 (IMAP4) protocol uses the Sent column as the secondary sort key.