The default arrangement to view messages in Microsoft Outlook 2010 is by date. A different arrangement can be used for each folder.
Tip: An improved version of the Date (Conversations) arrangement is available in Outlook 2010 which combines date and Conversation arrangement.
You can switch to other arrangements by doing either of the following:
On the View tab, in the Arrangement group, in the gallery, click the arrangement that you want.
Click the header at the top of the message list, and then click the arrangement that you want.
Note: To use the Date (Conversations) view, you must turn on Conversations. On the View tab, in the Conversations group, select the Show as Conversations check box. You can also click the top of the message list, and then click Show as Conversations.
To customize an arrangement, do the following:
On the View tab, in the Current View group, click View Settings.
Select the options that you want.