DST, Greylisting, and PBXs: Some Reader Questions Answered

My oldest son is in sixth grade, and he has to catch the school bus at about 6:45 every morning. This early call has occasioned lots of complaining, but he’s coming to accept it more now that it’s getting light earlier. IT administrators throughout the world are making the same adjustment with the daylight saving time (DST) update process that they're going through to prepare for the new start and end dates for DST. I want to answer a few last-minute questions that readers have asked about the DST change.

I’ve been repeatedly asked whether putting the Windows DST patches on both the client and the server is sufficient to fix the problem. The answer: No. The patches update the time zone definitions so that newly created appointments in the DST gap will have correct information, but they don’t do anything to correct the time of existing appointments. For that, you need to run either the Exchange Calendar Update Tool or Time Zone Data Update Tool. (For more information about using these tools, see "Exchange and Daylight Saving Time, Part 2," February 15, 2007.)

Another DST question is whether the DST patches are required for systems outside North America. The answer is yes, for two reasons. First, the DST patches also include time zone information for countries and regions other than North America. Second, if you schedule appointments with or receive invitations from people in North America, you’ll need the correct set of North American time zone definitions, which means you need the patch.

I’ve seen a few mentions of an odd problem related to the DST patch and message-tracking logs. If you install the patch on your Exchange server and find that your message-tracking logs are off by one hour, don’t be alarmed. Remember that the logs are stored using GMT as the base time zone, so when you change the server time zones the logs might appear to be an hour off. Microsoft is aware of the problem and suggests opening the tracking log files with WordPad as a temporary workaround until the company works out a better solution.

Here's a note on last week’s greylisting column ("Greylisting Trips Up Exchange 2003," March 1, 2007). My description might have made it sound like Exchange Server does (or should do) something special with 4xx rejections from a greylisting server. The 4xx range of error codes indicates a transient error--something that’s temporarily preventing message delivery. For example, the Exchange Server 2007 Hub Transport role generates “452 4.3.1 Insufficient system resources” errors when it has less than 4GB of free space on the SMTP queue volume; that error tells senders they should try again later. Exchange understands how to retry after a temporary error, but Exchange Server 2003 Service Pack 2 (SP2) still seems to have a problem resending greylisted messages the way it should.

Here's another non-DST-related question: Several readers have asked if particular IP-PBX solutions will work with Exchange 2007. Microsoft maintains a list of compatible solutions on its Web site. If you’re interested in a PBX that isn't on the list, and if the PBX supports Session Initiation Protocol (SIP) over TCP, you might be in luck, but you’ll probably have to ask the PBX vendor. (Remember that SIP over UDP isn’t supported directly by Exchange). Microsoft has been slow to update its list, but I expect that to change as we get closer to the release of Microsoft Office Communications Server 2007 later this year. Look for more on Communications Server 2007 in a future column.

I also want to mention a new project I’m working on with Microsoft and the Windows IT Pro team: a series of events highlighting Exchange 2007 and Communications Server 2007, the two core pieces of Microsoft’s unified communications strategy. These one-day events will cover a wide range of topics, including architecture, design, and deployment of Exchange 2007 and a first look at some of the cool new features in Communications Server 2007. To learn more or to register, go to http://www.windowsitpro.com/roadshows/exchange2007usa.

In the meantime, I have to wake up my son so he can catch the bus. Good luck on your final DST preparations!

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