1: Conversation view
OWA 2010 provides the same conversation view and experience as Outlook 2010: By default, messages are displayed in threads so that all the messages on a particular topic are grouped. No more searching for a previous message to check what the response is referring to. When a new message in a thread comes in, the whole thread gets moved chronologically to the date/time of the new message. Conversation view has its benefits and drawbacks, but if you don't like it, you can turn it off. Just right-click Arrange By, scroll down to Conversations, and deselect Show Messages In Conversations.
2: Ignore option
If you belong to mailing lists, you'll appreciate this new feature in Outlook 2010, which you also get with OWA 2010. Sometimes, the group will engage in discussions that don't interest you at all. Now you don't even have to see them. Just select Ignore Conversation from the action menu and any further messages in that conversation will be automatically deleted. This can be a real time-saver.
3: Forward as an attachment
It's a little thing, but sometimes it's the little things that matter most. With OWA 2010, you can forward an email message as an attachment. This can come in handy if you need to forward a message to someone but don't necessarily want the person to open it immediately. You can create an original message where you can tell the person about the attachment — or example, you might forward a message that possibly contains a virus to someone who provides technical support for you.
4: Delivery report
Another new option on the action menu is Open Delivery Report. If you've ever sent an important email and then agonized over whether it got to the recipient, this feature will be one of your favorites. You can search for messages you've sent to a specified recipient, messages you've received from a specified recipient, or messages with specific words in the subject line. The delivery report will show you on what date and at what time the message was submitted and when it was successfully delivered.
5: Same premium experience without IE
One of my pet peeves about previous versions of OWA was that to get the best experience, you had to use IE. It didn't work the same in other browsers, such as a Firefox. You got a "light" version of OWA instead. And if the only computer available to log on to the Internet was a Mac with just Safari as the browser choice, it was no fun at all. OWA 2010 supports the complete, premium experience on Mac OS X with Safari as well as with Firefox.
6: Integrated IM/presence information
OWA 2010 integrates directly with Microsoft Office Communicator 2007 R2, allowing you to see the presence status (available, busy, away, etc.) of other users within your organization and even engage in a chat with them. You can also engage in multiple chat sessions with different people at the same time.
7: Opening another user's mailbox
With Exchange 2003, you couldn't open another user's mailbox from OWA. With Exchange 2007, you could — but it opened in a new IE window and you couldn't select the mailbox from the Global Address List (GAL). With Exchange 2010, you can select a mailbox to open from the GAL, and it "nests" into the left pane along with your default mailbox. OWA also remembers which mailboxes you opened and displays them when you log on the next time.
8: Side-by-side calendars
Another feature that's been on the OWA wish list of many Outlook users is the ability to open up a shared calendar and view it side by side with your own calendar. This is invaluable if you need to make plans that include coordinating your schedule with someone else's. You can share your calendar with other users of your Exchange 2010 server.
9: Exchange Control Panel (ECP)
In OWA 2010, the Exchange Control Panel replaces the Options page in OWA 2007. Users can do more with the ECP, such as creating and managing distribution groups, tracking their own messages, setting up retention policies for their messages, and updating the property fields information in their Active Directory user accounts.
10: Access to mailbox archives
OWA 2010 allows users to access archived mailboxes from within the OWA interface so that you can get access to the archived messages no matter where you are.
