For many of us, Outlook is the most important part of the entire Office suite. It's where we manage the steady trickle of e-mail that drives and directs our work, it's where we plan our days, and it's where we keep all our business contacts. We may be more directly productive in Word or Excel, but it's Outlook that guides that productivity.

In common with the other applications in the Office 2013 suite, Outlook 2013 has been given a handful of new features and a fresh coat of paint. This is not entirely surprising: the Office applications are mature, many of them more than 20 years old, and they all do pretty much everything they'd ever need to. The focus of Office 2007, 2010, and now 2013 is less on raw feature count and more on streamlining common tasks and making it easier to find the functionality you need. (We've already looked at the major design changes to the Office 2013 suite as a whole.)

Start Outlook 2013 and the first thing you notice is that its icon and splash screen are now blue instead of the orange-gold that has been Outlook's color for years. (It's now the same color as Lync's icon.) I keep mistaking it for the Word icon, which retains its, uh, iconic blue.

Once loaded, the program looks much like Outlook 2010 with a Metro twist: all-capitals text for the ribbon tabs, a great reduction in the lines and shading, and simpler icons. Everything remains in pretty much the same place as it is in the current version. The left-hand navigation bar that shows e-mail folders is collapsed by default, and the icons for switching between mail, calendar, contacts, tasks, notes, shortcuts, and folders have been replaced with text labels—another nod to Metro aesthetics. Switching between these modes now has a transition effect, with the old content swiping and fading out one way as the new content comes in from the other side.

In common with the terminology used in Windows 8 and Windows Phone, the contacts view has also been renamed to "People."

The main e-mail listing has seen a couple of small changes. First, the search box now has a search location filter, allowing you to choose between searching the current folder, the current mailbox, all mailboxes, and so on. Second, it has a quick filter to toggle between showing all mail and just unread mail. Again, this feels like a nod to the design used in Windows Phone, and it allows a similar instant-access filtering capability. Windows Phone goes further, though, as it also has a filter for urgent/flagged e-mail.

Again reminiscent of the Windows Phone mail client, the mail listing also has quick access to certain operations. In addition to the quick categorize and quick flag that Outlook 2010 has, there's now a quick delete.

This is probably just as well, because the new mail notifications have gone from "useful and feature rich" to "completely dumb." In Outlook 2010 I can, and do, delete unwanted mail directly from the new mail alert just by clicking the delete button. The alert in Outlook 2013 doesn't include any such option, because it's a new-style Windows 8 alert, which doesn't offer any such features.

The final important visual changes are in the mail preview pane. The preview pane has small Reply, Reply All, and Forward buttons at the top, giving instant access to these routine operations even if the ribbon is hidden.

Hitting one of these shows off the first truly new feature, and probably the one that will get most use: inline reply. Instead of popping open a new window for composing your response, the preview pane itself becomes editable, allowing the e-mail to be written directly in-place. Pop out the reply and you get a regular compose window.

If you click away from the inline reply (for example to read another e-mail), the reply gets saved as a draft automatically. The message listing changes to show there's a draft reply in progress.

To help make writing those e-mails a little faster, Outlook 2013 includes three new "Peek" features to let you glance at your calendar, contacts, and tasks without having to switch modes. Hover the mouse over the mode buttons and a little pop-up window appears, giving you quick access to your information.

Finally on the mail front, Microsoft has added a very welcome feature that will be familiar to users of Gmail and other mail applications. If you mention an attachment in the body of the mail but don't actually include the attachment, Outlook will warn you before you can send the message.

This is part of a broader set of warnings called "Mail Tips" and "Policy Tips." They'll warn you about, for example, sending mail to people who are out of the office, potential violations of information management policies, and so on.

Visible in the mail view is the integration of the Outlook Social Connector. This was an add-on for Outlook 2007, and was semi-integrated in Outlook 2010 (the "Social Connector" part was built in, but you still needed plugins to actually connect to social networks). It's now useful without any extra plugins, with both Facebook and LinkedIn support built in.

The Social Connector's people pane is little changed, though sadly it no longer uses Bill Gates' silhouette for contacts that don't have a picture.

Outlook's calendar view isn't much altered, except it now includes a display of the weather for the next three days. Everyone loves talking about the weather, I guess, but it seems a strange thing to build into Outlook.

The People (formerly Contacts) section has seen some love too, with a new view, called People view, and greater integration with the social connector. The People view provides a degree of unification of contact data: it cross-references up mail contacts with their corresponding social network data. It can show profile pictures, job information, and additional contact information where available. As with other Social Connector functionality, it does this by matching people's e-mail addresses.

In addition to these visible changes, a few things have gone on behind the scenes. Outlook now supports more kinds of mailboxes than ever before. As well as Exchange (using both RPC and HTTP-RPC ["Outlook Anywhere"]), IMAP, and POP3, Outlook can now directly use Microsoft's ActiveSync API that's used by smartphones and tablets for push mail, contact and calendar sync, and so on. ActiveSync is natively supported by Exchange (though Outlook preferentially uses Outlook Anywhere with Exchange servers) and is also supported by certain Web-based mail providers including Hotmail and Gmail.

As a result, Outlook can directly communicate with Hotmail, a task that previously required a plugin. You should also, in principle, be able to use it with Gmail (though if you use auto-configuration, it will default to IMAP instead).

For Exchange users, there's greater control of offline mail caching. In Outlook 2010, this is a binary toggle; you either have mail cached for offline use, or you don't. If you have a 25GB inbox, this requires a 25GB cache. Outlook 2013 now has a slider to say how far back mail should be cached. It defaults to one year, and has a range from one month to forever.

Outlook has long been "special" among the Office apps, because it's not document-based and is much more network-centric. This has resulted in some user interface differences in the past—Outlook 2007 didn't have a ribbon in the main app window, for example—and those continue in 2013. The Office account menu that's in the top right of every other Office app isn't in Outlook, nor are things like SkyDrive integration.

However, the lack of integration did surprise me in one place. For this preview, I used an Office 2013 subscription with my license tied to a corresponding Office 365 account. I would have expected Outlook to come preconfigured for that account. It didn't.

That said, Outlook does have some small interactions with the Office Account system. Microsoft also has a new extensibility model and app store for Exchange and Outlook add-ons. Server-side extensions can be written to, for example, detect addresses in e-mails and embed mapping information. These will all be offered, with a mix of free and paid extensions, through the Office Marketplace.

Overall, Outlook 2013 is a modest update to Microsoft's flagship mail and calendaring application. With the exception of the new mail alerts—inferior to their Outlook 2010 counterparts—it's a better application all round. The new features aren't groundbreaking, but they're all at least sparingly useful. Outlook users will want to upgrade.

Listing image by Aurich Lawson