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Monday, February 05, 2007

DST Updating in Exchange - How Big is Your Coming Email Update Storm?

The Microsoft methods for updating Time Zones for the coming DST shift will require that meetings in the relevant time delta be re-proposed.

It does not take a lot of head scratching to realize that this will potentially result in a lot of email traffic on your servers. It's also reminiscent of how the dentist tells you an X-ray only gives you the same amount of radiation you'd get during a day on the beach (conveniently ignoring the fact that she's giving you the same dose in a few milliseconds instead of eight hours).

So your first question is probably: How much traffic can I expect to have?

The Sumatra Utilities (available for free) can give you the answer.

At the command prompt run:

su /u:jsmith /DST

To get a count of all "jsmith"'s meetings and appointments in the relevant region.

The output looks like this:

Alias Num Appts Num Recur Master Num Recur Instances Num Recur Exceptions Total Items Total Cross Check
jsmith 12 2 19 1 34 34

The final number is the total of all affected calendar entries (meetings and appointments) in the area.

If you choose to do only recurring meetings, look at the third number form the left: Number of Recurring instances. Each of those will require two emails: one coming IN to that guest and one going OUT from that guest as a response.

The totals of these for all your users is a close approximation of the total amount of email traffic you can expect. Why is it not exact? Two reasons:
  1. If guests have DECLINED the meetings previously then they're not on the calendar so don't count in the totals but they will receive updates
  2. Users who have been invited but have not yet responded may not have this calendar object on their calendars yet.
A quick look at the output file will show you it's tab-delimited so easy to load into a spreadsheet for analysis.

This will work on resource accounts as well.

Our next topics: How to use Rhino Event Sink to automatically accept all updates and how to use the Utilities to deal with managed resources and discover double-bookings without opening all your resource calendars.

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