For the first time in ages I switched from using Blackberry’s push email system to Microsoft’s push email system, for a whole month, in order to give it a thorough testing. This was a deliberate choice because, unlike most other push email solutions, Microsoft’s doesn’t require an extra server. Microsoft’s push system isn’t really a shrinkwrapped product at all: the underlying technology is referred to as “Direct Push”, but rather than being something that arrives in a box or on a CD it’s simply a method for connecting two existing Microsoft products – Exchange Server and Pocket Outlook. There’s no extra software to buy or install, and hence no additional servers required. That makes it sound like a bit of a no-brainer, since most alternative push email systems cost a fair bit and, as I just mentioned, they’ll all require their own dedicated server. Surely a zero-cost, zero-install solution is the way to go?
|You’ll need to get SSL working, the first step being to create a Certificate Signing Request.|
For some companies, it almost certainly will be, but it isn’t quite so simple as the Microsoft marketing machine would have you believe. For a start, your company needs to have deployed the correct version of Microsoft Exchange for it to work, namely Exchange Server 2003. Actually, you have to go one step further, because you’ll also need to have installed Service Pack 2 to get the Direct Push email system working. Prior to SP2, an alternative push email system was available, but frankly it was a bit of a hack (actually a huge hack), which relied on the mail server sending an SMS message to the mobile handset to say a new mail was available, whereupon the mobile would connect to retrieve it. It thus relied on the mobile phone networks’ email-to-SMS gateways. Of course, if you’re lucky, you might have splashed out on Exchange 2007, but there are relatively few early adopters out there yet.
There are several problems with this approach, the chief being that not all networks offer such a gateway and, even when they do, they’re notoriously unreliable. Another potential pitfall for SMS-based push solutions is that some networks charge 25c for each SMS sent via their gateways, which might sound reasonable for people only receiving a few messages per day, but what if a rogue script runs riot and sends you thousands of emails? Or, what if you annoy someone in a newsgroup and they mail-bomb you with hundreds of thousands? It isn’t just your mail server that would explode, but also your mobile phone bill.
Microsoft’s previous attempt at push email is therefore best avoided, but the latest incarnation is actually quite good. It doesn’t rely on SMS at all, the mobile and the server instead talking to each other via a standard HTTPS (port 443) connection. They can even talk using normal port 80 HTTP, although that isn’t something I’d encourage for obvious reasons of security, both encryption and authentication.
I mentioned that to get Direct Push running requires a specific software environment on your mail server, and the same is true of the handset, be it a PDA-style device or a smartphone. It needs to be running one of the connected flavours of Windows Mobile 5, but, in addition, it needs to have the Messaging and Security Feature Pack (MSFP) installed. This wasn’t included when Windows Mobile 5 first shipped, but has since been made available as an update. You’ll often find it described as an AKU 2 update and, unfortunately, it isn’t a simple install because you actually need to re-flash the ROM in your mobile device.
This seems to be a significant weakness of Windows Mobile 5 – most other mobile OS platforms allow core operating system components to be patched or replaced without performing the mobile equivalent of open-heart surgery. Windows Mobile demands a complete ROM upgrade, which means that every single handset variant requires its own special version of the AKU 2 update – and if the same hardware is sold under a different badge by different mobile networks then each will supply its own ROM upgrade. You’ve obviously got to be very careful to apply the correct update to your device or you could end up owning a shiny, expensive paperweight.
Luckily, any handsets manufactured within the past few months will probably have AKU 2 already installed, so this whole MSFP thing becomes less of an issue if you’re buying new kit. But for a company that already deploys a fleet of mobiles, getting them all upgraded to the correct version of Windows Mobile 5 can be a bit of a headache.
Assuming you’ve got the correct version of Exchange Server and that your mobile devices are all running AKU 2, how do you get this push email thing working? As I said above, it’s important to do all communication via SSL, so if you haven’t already done so you’ll need to install a secure server certificate into the copy of IIS on your Exchange Server (or your front-end server if you’re running a multi-server configuration). This is the normal process you’d go through in setting up any secure website: generate a certificate signing request (CSR); send it off to a certificate authority (CA); then install the returned certificate into IIS, making sure you enable port 443 (HTTPS) traffic in the properties of the default website. At this point, you should find that you have Outlook Web Access (OWA) running and be able to connect to it over HTTPS using a web browser.