Exchange ActiveSync to be replaced by Outlook Web App on mobile devices?

Exchange ActiveSync (EAS) has been a stunning success for Microsoft and is currently the de facto connection protocol between mobile devices and Exchange Server. Every large mobile device vendor has licensed EAS, but perhaps its time is running out because current devices demand more functionality and current networks enable that functionality. It makes sense from an engineering perspective too as Microsoft can put EAS into maintenance mode and replace it with Outlook Web App (OWA) for mobile devices.

In a couple of recent posts I discussed the developing user interface seen in Outlook Web App (OWA) for both Exchange 2013 and Exchange Online and how OWA takes a new approach to public folder support. These enhancements plus a most welcome increase in the client's responsiveness from Exchange 2013 CU1 onward have combined to make OWA 2013 a very nice place to work. I would not quite go as far as those who say that OWA 2013 is the best looking browser client available today, but it is certainly close to delivering the necessary mix of functionality and appearance to be able to boast a little.

The developments in OWA 2013 make me think that ActiveSync (EAS) is running out of steam and will soon be replaced by a browser-centric approach for client support across non-Windows platforms. EAS has been a sparkling success for Microsoft since its server implementation was first bundled with Exchange 2003 but I think that the market that EAS was designed to support is long since passed.

EAS uses long-lived HTTP transactions as the basis of its synchronization with Exchange mailboxes. The implementation works with a huge number of client types from iPhones and iPads to Android devices to Windows Surface. As a method of communications over flakey networks such as the kind of mobile networks we had in the latter part of the last decade, the approach taken by EAS delivered a very solid method of getting email, calendar, contacts, and tasks information to mobile devices. Ever since 4G networks started to appear, the need for EAS has diminished. That trend continues as new and more powerful mobile devices are built to use the kind of fast and abundant networks that are now commonly available.

EAS is limited in what it does. Look at the Mobile Outlook client available in Windows Phone (7.8 or 8) and compare it to OWA. You’ll see that the mobile client does a good job of dealing with email, calendar, contacts, and tasks but no more. Mobile Outlook and every other mail app that supports EAS is constrained by the limits imposed by the protocol. The limits exist for good reason as the last thing you want is for mobile clients to engage in extended discourse with a server. Standardizing the calls and restricting them to particular operations lay the foundation for well-structured communications, which is what EAS delivers.

But consider that Microsoft has now delivered a version of OWA that is more functional than any EAS client and think of the engineering costs that are necessary to keep both EAS and OWA moving forward. Think of the standards-based approach taken by OWA, including in its implementation of offline access. Think of its support for archive mailboxes and public folders and soon, perhaps, site mailboxes, and its ability to handle advanced Exchange features such as retention polcies and tags. Think of how OWA seems to be able to embrace and support new server-enabled features and how it can use the new app model to extend its capabilities even further. Think of how browser support constantly evolves at pace across all the modern mobile device types. It’s a very compelling picture.

Now think of what might happen if Microsoft had to make a decision to reduce engineering spend in one area to make room for additional investment in another. It doesn’t take much imagination to come up with a scenario where EAS is placed into maintenance mode and all of the engineering attention focuses exclusively on OWA as Microsoft's preferred client for mobile devices. It makes even more sense if Microsoft can then direct all the mobile device vendors to use the well-trodden path taken by OWA to connect to Exchange and so avoid some of the disastrous interactions that EAS has experienced in the past, notably when Apple’s mail app attempted to have unnatural relations with Exchange via EAS.

Microsoft went down this path before with Outlook Mobile Access (OMA), an attempt to extend coverage to very basic phones or phones with very small screens. The venture I anticipate would be nothing like OMA. Instead, it would be a full-blown OWA experience for mobile devices. I don’t think that this will happen overnight because considerable work would no doubt have to be done to make such a scenario viable. We might see it in 2014. Or maybe 2015.

I don’t work for Microsoft and do not know what thought processes are ongoing inside the Redmond campus. But all protocols come to a natural point when their usefulness is degraded by changes in the technology landscape. I think EAS is at that point now. We’ll just have to wait and see whether Microsoft agrees.

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Discuss this Blog Entry 16

on Jul 10, 2013

Yes - one look at Outlook app on my Android gives me good feel on what problems we will have (try to change font size ...).
And EAS drop ??? Fun again ... Cannot wait !

on Jul 10, 2013

Outlook doesn't have an app for Android. You're referring (I think) to whatever mail app is provided by the vendor of the smartphone or other Android-powered device you use. Microsoft has no control over how these apps use EAS, which is one of the reasons why an intelligent browser-based email application makes a lot of sense...

on Jul 12, 2013

my apologies

I did reference hotmail app replacement for Android.

on Jul 11, 2013

Tony please put down Paul T's Windows Phone kool-aid because making reference to Mobile Outlook for a case of actual EAS usage in the field is like judging the quality of the roads on the opinions of Oldsmobile drivers today. Also the general feeling is that OWA 2010 is a better experience than OWA 2013 (sans a bell or whistle). There's no way EAS will die for a global OWA client no matter how hard you or anyone at Microsoft ever think of this pipe dream ever again.

on Jul 11, 2013

I drink coffee, not Kool-Aid.

on Jul 11, 2013

@Abasi, 1) I don't do Kool-Aid. I'm too grumpy to consume that kind of muck. In fact, I don't think I have ever even tasted Kool-Aid, mostly because it seems like something I would not like. 2) I'm not quite sure what point you're making about Mobile Outlook. The fact is that every EAS licensee can build their own email client to connect to Exchange via EAS; it's entirely up to them to decide how that client should behave. Mobile Outlook happens to be just one EAS client; it also happens to be Microsoft's EAS client (or rather, one of them, the mail app included in Windows 8 is another). 3) I agree that the RTM version of OWA 2013 was not as good as OWA 2010 and have said so a number of times. However, I see improvement in CU1 and more improvement in CU2. It's coming along. 4) The article was intended to point out that OWA has more functionality and coverage that EAS and solves some of the problems that people have today with EAS; why wouldn't it be a candidate to be more than a pipe dream in a year or so?

on Jul 12, 2013

My point is that users do not have issues with EAS, it works pretty well, so well that noone misses their blackberry anymore. Windows Phone is just not an example of what companies are using as EAS devices. (This is not my opinion, you guys travel for work just like me, you see the field). Looking forward to seeing the improvements in CU1 but Microsoft in no way would ever cease EAS, if anything it would be the other way around as mobile devices and their browsers are getting more powerful and may one day just handle the requests natively as a desktop browser can. This would lead to Microsoft getting rid of the "Lite" or "tablet" version of OWA which is a more practical outcome.

on Jul 12, 2013

we have seen this before from MS ... replace this drop that ... like database lumit in 2013, or crazy push of Metro ... no Public Folders ...
EAS as badly as it is written by MS is so widely used that it will not be removed until Exchange 2019. Now whomever is in charge of dissemination of future plans @MS should probably talk to customers first. does MS seem confused with their message ? just look at their change of tune with CU support ... and now their Office 365 market may shrink to North America only ... yeah maybe internal changes as we see could help.

on Jul 15, 2013

@Abasi, I agree with you that EAS works wonderfully well. So much so that it is now the de facto connectivity standard for mobile devices to Exchange. But my point was that OWA offers some advantages to Microsoft (and perhaps to the device vendors) because it would mean that a single consistent client interface would be used on all devices. That interface already has offline access and uses HTTP like EAS so it doesn't take a huge leap of faith to see how it might happen. And besides, this was an opinion article and not a news report - so it was intended to stir comment, which is what it did!

on Jul 15, 2013

@keruzam, it's hard not to note that you have a record of making extremely critical and not well founded (IMHO) comments about Microsoft and Exchange. EAS is not badly written. If it was, it wouldn't be used as widely as it is today. EAS is a protocol and it is up to the device vendors as to how they use it. Microsoft bears some of the blame for not bulletproofing the protocol on the server as well as it might have been, but those holes are being closed off and the current implementation is much better than (say) it was a year ago. I also doubt that the Office 365 market will shrink to North America. Although the PRISM controversy will cause some companies to ponder about how they will use cloud services that are exposed to three-letter-agencies, many will conclude that the economic benefits of using the service far outweigh any risk that might be incurred if some analyst read their email.

on Apr 29, 2014

Hi Tony,
Yesterday I found myself pondering on Microsofts angle around continued support for Activesync and the ever developing OWA interface. I pretty much came to the same conclusion as you in that eventually I see Activesync being depreciated. When I say 'eventually' this might take a few years but Ive no doubt that in 5 years time none of us will be using a device which leverages activesync to connect to Exchange. Funnily enough after coming to this conclusion, I then started searching around the web and came across your post which pretty much replicates my own thoughts :-)

on Jul 15, 2013


EAS if you have Exchange you must use it regardless of how perfect imperfect this protocol is. What you end up with is all sorts of "clever" workarounds to accomplish simple funtionality like shared address books and such ...
I probably expect too much, mind you working with other products in the past perhaps has something to do with my expectations.
As far as Office 365 ... private companies maybe, governments and such we will see. Putting some pressure on MS can only help the product and service. Anyway in 6 to 12 months we will see this play out. For what is worth my advise is to stay with 2010 SP3 plus latest RU unless you have

on Jul 15, 2013

@keruzam, yes, we will see what happens. Stay tuned.

on Jul 15, 2013


I will stay put on 2010 SP2 RU5 v2 and see what develops. From my limited research there are more than few like me - using the product, but fairly critical as well and this is good. If nobody said anything 50 databases limit in 2013 would stay. Was not my noise of course, but it is nice to notice tgat MS is listening to customers. Some really interesting times on the horizon.
Thx for taking time to respond.

on Jul 16, 2013

on Jul 18, 2013

So now we have the OWA apps for iPhone and iPad ( You can see why Microsoft has produced these apps if you understand how much grief the EAS problems due to bad Apple code in their mail app caused customers in late 2012 and early 2013. The big issue with these apps is that they are tied to Office 365 for now; but they will be available for on-premises customers soon after Microsoft releases another cumulative update for Exchange 2013. The question is whether this will prove an attraction for customers to move to Exchange 2013. I suspect that it won't make a huge difference, but it is a nice-to-have.

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Tony Redmond is a senior contributing editor for Windows IT Pro. His latest books are Office 365 for Exchange Professionals (eBook, May 2015) and Microsoft Exchange Server 2013 Inside Out: Mailbox...
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