Over the past week or so, Google has started rolling out IMAP support for its Gmail Web-based email service. (Which, with the addition of IMAP, might now be thought of simply as "email" rather than just Web-based email.) This is a tremendous improvement to Gmail, a system that is already first-rate and, in my opinion, superior to other non-corporate email solutions. Indeed, for me personally, the addition of IMAP support to Gmail changes everything for the better.

IMAP is more sophisticated. I disable Gmail's POP support because I'm fearful that I might accidentally download my email to one of the many machines I use and test and then forget to back it up. By keeping my email in the cloud, I can access it from anywhere at any time. IMAP adds a new layer of sophistication that enables me to use rich desktop email clients like Microsoft Outlook if I so choose: Email is not downloaded from the server and deleted, it's synchronized between the client and cloud, giving you the best of both worlds. Email is still stored in the cloud but retains the correct message status (read, not read, how it's filed or labeled) regardless of where I access it from. And I can work offline in applications like Outlook if I want to. Perfect.

Gmail IMAP actually works with Gmail's unique Labels system. Gmail has one major advantage over every other Web mail solution on earth: Instead of locking you into a rigid folder structure for organizing email, Gmail uses a database-like Labels construct. In Gmail, all of your email is stored in a single pool, as in a database. You organize email by labeling individual messages (I use things like Work, Readers, Microsoft, Buy stuff, and so on) and then these labels are used like pseudo-folders in the Gmail UI. (They're really database views, if you're familiar with database products like SQL Server.) What's so great about Labels? Aside from the technical sophistication of this system, Labels let you mark email so that it appears in two or more "folders"; that is, you can apply more than a single Label to any email. So if I get an email from my wife wondering why I haven't gotten a particular royalty check yet, I can label that as both "Personal" and "Work" so that it will turn up in both places, as it should. With a rigid folder-based structure, an individual email can only be stored in a single location.

OK, great. The problem with this Labels-based organizational structure is that Google is the only using it, and traditional email clients, and Apple's iPhone, don't know how to work with it. (This is why I was hoping for a "true" Gmail client for the iPhone.) But aside from the inherent superiority of IMAP, Google's IMAP implementation is actually compatible with Labels: So if you configure a Gmail IMAP account in Outlook, the iPhone, or any other IMAP-compatible solution, you'll see those Label views appear as folders. And if you copy an email into one of those "folders," what you're really doing, up in the cloud, is labeling that email accordingly. So it's in perfect sync: You can label email as before using the Web-based client, or drag and drop (or even set up automated rules) on the client. It all works, back and forth across the cloud and the email clients. Perfect.

Gmail IMAP makes iPhone email truly interesting. You have no idea how close I've come to cancelling my iPhone service subscription and walking away from this device for good. There are so many reasons for this--the horrid AT&T Internet service, an utter lack of viable calendar syncing in Windows, absolutely no way to customize what apps are running and available on the device (changing in 2008, supposedly), the list just goes on and one--but one of the biggest, for me, was the lack of a decent email client that works with what I actually use every day. As I thoroughly documented in a blog post earlier this year, Apple's pseudo-smart phone offers various levels of email support depending on what kind of service you use. At the top of the heap are Yahoo! Mail, .Mac, and AOL, each of which is natively supported by the iPhone (and is thus very easy to set up) and uses a push-like mechanism to get email out to the device. The next level of support down from that is IMAP. (Below that is traditional Gmail--i.e. POP-based access to Gmail--and any other POP email services, as well as Web mail.)

By adding IMAP support to Gmail, Google has pushed (ahem) Gmail into the top tier of email support on the iPhone. (Well. It's at least near the top tier: Until Apple specifically supports Gmail IMAP, you have to configure the account manually, which is laborious on the device's lackluster virtual keyboard. Who cares? You only have to do this once.) What this means to me, and to anyone else using Gmail, is that the iPhone is suddenly a first rate mobile email experience. Finally.

Folks, this is what Microsoft means when it talks about "software + services" and I hope Google is hard at work getting its other online services--things like Google Calendar and Picasaweb, especially--integrated into the iPhone and other mobile platforms. Microsoft has Windows Mobile, and if you're using any of the company's Windows Live services, including Hotmail, that's likely going to be you A-list mobile experience for some time to come. For those of us that use Google, however, the iPhone is suddenly the place to be. It's ironic, in some ways, that this happened because of a company other than Apple.

We need more. In the interests of being greedy, I should point out that there's still more to be done, mostly with related services. I've written a lot about the need for an Outlook Connector for Google, something that would effortlessly sync Google's email, calendaring, and contacts services with client-side applications like Outlook (well, with Outlook specifically in this case.) Currently, Gmail Contacts is a third-rate solution at best, though that's allegedly changing. Google Calendar is fantastic, but you have to use hokey workarounds and private URLs to push the content into Outlook if you're trying to keep your data private. (And don't get me started about Google Calendar's lack of true event labels, which should be color-coded as they are in Windows Calendar and iCal.) IMAP is an incredible first step. But now I want so much more.

Anyway. Google's embrace of IMAP makes the best email service even better. And when you combine that with the performance and functional benefits of Gmail over services like Hotmail and Yahoo! Mail, it's becoming more and more of a no-brainer to use Google's services over the competition. Score one for Google.