Category Archives: Musings

“Does Entourage use RPC-over-HTTP?” I’ve run across this question several times in the public newsgroups, on mailing lists, and in direct conversation. Now Mike Wendland’s asking, so I figured I’d write a long answer and just refer to it in the future.

In the beginning, there was MAPI, the Mail Application Programming Interface. Microsoft Mail (remember that?) used MAPI, as did the long-forgotten Windows Messaging and Exchange Client applications. When the Outlook team began working on Outlook, it used MAPI also. MAPI communication between client and server are actually implemented using remote procedure calls (RPCs) that travel over the Windows RPC subsystem, which uses TCP ports 135 and 443 and UDP ports 137 and 139. Because early versions of Windows had a number of RPC-related security vulnerabilities, admins quickly learned to block these ports from the Internet, meaning that you had to dial in or establish a VPN session to get your mail with Outlook from outside the corporate network.

In the meantime, lots of other applications started tunneling their data over the standard HTTP port, TCP port 80. This has the advantage (for users) of letting these applications run without special permissions or changes to the firewall. With Outlook 2003, Microsoft implemented RPC-over-HTTP tunneling so that you can establish a native Outlook MAPI session from outside the firewall without using the default RPC ports. This is good from a security and convenience standpoint. Why security? Think about it: if you establish a VPN session, you’re trusting the remote machine to be clean, and you’re trusting the remote user not to do anything malicious on your network. With RPC-over-HTTP, all the remote user can do is get mail, so you don’t have to worry that they’re going to screw up anything else.

Entourage for Mac OS X doesn’t use RPC-over-HTTP. Instead, it uses WebDAV, an XML-based technology that travels over HTTP connections. It has nothing to do with MAPI or with RPCs, and it works with Exchange 2000 and Exchange Server 2003– RPC-over-HTTP requires Exchange Server 2003 running on Windows Server 2003.

Both technologies have the same effect: an outside user can establish a connection to the Exchange server using HTTP (which had better be protected with SSL) to talk to the server.

Now, on to Mike’s specific question: Apple Mail 2 supports Exchange accounts using WebDAV, so if your employer supports WebDAV and is running Exchange 2000 or later, you should be good to go. You’ll probably need to enter the same server name that you use for Outlook Web Access to get Mail to find the right server. Good luck!

Congratulations to the Microsoft Office Communicator team! They just RTM’d their product. If you haven’t already tried it, grab the evaluation version and give it a spin.

I was floored to hear about this, but maybe that just shows I need to get out more. Turns out that you can flip a metabase flag to get some additional control over SMTP relaying. By default, if you require authentication and list one or more allowed IP addresses, both of those restrictions apply. However, you can set the SMTPIPRestrictionFlag value to use the logical-OR of those two factors, so that you can relay if you authenticate or if you’re coming from an allowed IP address. Mad props to Konstantin Ryvkin for admitting to this and to Devin for blogging it.

Singlefin announced today that they’re giving away their hosted spam filtering service, free, to organizations with 10 or fewer mailboxes. The press release (which isn’t on their site yet) quotes their CEO as saying “Of course, we know that small companies can become large companies and if we extend this generous offer now while they are still growing, we are confident it will translate into brand loyalty and solid customer referrals down the road”. Here’s the most interesting part:

Any organization anywhere in the world is eligible to take advantage of this protection without the need for cumbersome software or expensive hardware. Singlefin solutions are 100% managed or “hosted” meaning protection for customer networks is all enabled through network redirects. One simple change to a customer’s DNS enables 100% protection from spam, viruses and other malware via Singlefin’s Enterprise Email Filter. The Web and Instant Message Filters are enabled through similar network changes.

This is a terrific move on Singlefin’s part; the incremental cost for them to host these small organizations is low, but the brand-building value is very high. There are so many anti-spam solutions on the market that it’s hard for vendors to differentiate themselves, but this should definitely help build awareness of Singlefin.

My partners at 3sharp have been involved in a huge project over the last few months: building credible enterprise-level sample applications using Office as a development platform. Behold: Fabrikam, a Microsoft Office System Solutions Learning Platform! Hats off to Peter, John, Anup, Kevin, David, Chris, Greg, and Phil.

Now this is pretty slick: the Visio 2003 Connector for MBSA turns an MBSA scan into a color-coded Visio network diagram. (Actually, you have to create the network diagram first, but that’s trivial with Visio 2003 Professional). What a great add-on to MBSA’s built-in scanning functionality. Get it here.

Greg Hughes has a great dissection of his recent search for a replacement for his BlackBerry. In the end, he went back to the old familiar BlackBerry, but not until after he tried the Audiovox 5600, the SX66/XV6600, the Treo 650, and the BlackBerry 7100 series. He started with a BlackBerry device and tried the others to see how they compared as mobile email devices and as phones. Perhaps unsurprisingly, he ended up with his same preferred device. It’s fascinating to see how big a role inertia plays in PDA/smartphone selection, compared to the larger mobile phone market. Of course, device cost (and the cost of installed software) make a huge difference. I considered the BlackBerry 7100s, but since I can’t run any of my stable of useful Palm apps, that wasn’t going to happen. (I still have to post a longer review of the XV6600, besides my initial thoughts).

Huge news from the Real-Time Communications product team at Microsoft. First, we’ll be getting a Live Communications Server client for Windows Mobile devices sometime in the second half of this year. I’ve been happy using the MSN Messenger client that comes with the Windows Mobile-powered Audiovox XV6600, but being able to communicate with other corporate LCS users will be a huge win– right now, if I want to IM with someone inside Microsoft’s perimeter, I have to dig out the ol’ laptop. MS hasn’t yet announced pricing or functionality; I think it’s safe to assume that the Windows Mobile client will have a subset of Office Communicator’s functionality, in the same way that Pocket Outlook is a subset of desktop Outlook.

The other news astonished me: Research In Motion, producers of the BlackBerry line, have signed an agreement with MS to produce a Live Communications Server client for the BlackBerry platform. This is terrific news for the LCS team, and great news for BlackBerry users who want to combine their existing mobile e-mail service with IM and presence. Of course, it raises the bar for the Windows Mobile team, who now have to contend with the loss of what would otherwise have been a significant capability advantage. With Magneto around the corner, though, I bet they have some other tricks up their sleeve.

Update: looks like RIM’s been busy; yesterday they also announced an agreement with IBM Lotus to provide a native Sametime client for BlackBerry. The plot thickens…