Conversation based grouping in Outlook similar to Gmail?
I use these steps (from a post on the More Productive Now blog):
Switch to your Inbox.
From the main Outlook View menu
- In Outlook 2007: select Current View > Define Views.
- In Outlook 2003: select Arrange By > Current View > Define Views.
In the list of views, select the “Messages” line, then click the Copy button. In the resulting window, type “Messages By Conversation” for the name of the new view. Select the This folder, visible to everyone option. Click OK to close this window.
In the Customize window that’s now displayed, click the Group By button. Uncheck Automatically group according to arrangement. Set the Group items by drop-down list to Conversation. (Leave the option button set to Ascending.) Click OK to close this window.
Click the Sort button. Change the Sort items by drop-down value to Conversation Index. Change the option button to Descending. Click OK to close this window.
Click OK to close the Customize View window.
Click the Apply View button, and you’ll see your new view in action!
I'm not sure if it helps, but Outlook 2010 has a conversation-based view that includes sent messages.