Handling multiple Exchange Calendars

01 Aug 2010
Posted by Kiran

One of the disadvantages with having to manage multiple Exchange Accounts is that it is very difficult to get a unified view of the all the accounts. Be it email or calendar schedule, each Exchange account could potentially have a different set that have to be dealt with. Microsoft Products only allow access to one Exchange account at a time, and that complicates things.

For emails I just move them into PST folders organized by project, initiative, topic, whatever the case may be. Once these emails — whichever Exchange Account they came from — are in their folders, I can easily get a chronological view of what conversations were going on related to that piece work.

Getting a similar view of appointments is trickier. I always like to know when my meetings are scheduled and ensure I am not double-booked at any particular time before I respond to meeting requests.

Managing this with two Outlook Profiles is next to impossible. However, I found a rather unique way of handing this issue. I use the "Publish to Internet" feature in Outlook 2007 to do this.

How do you publish your calendar to the Internet?

The Publish feature uses the Web Calendar Access Protocol and creates an ICS file on the server with details of all the appointments on your calendar within the selected period.

To Publish a calendar, just right click on it and choose Publish to Internet in the Context Menu, then choose the location you want your Calendar to be hosted in. Outlook 2007 gives you two options: the Windows Live servers or any WebDAV Server of your choice.

Publish Options in Outlook

If you choose a WebDAV server, you will be given the option of putting in the server address and selecting some other options about the period for which you want your calendar to be shared and the amount of detail that is to be shared.

Server Details

If you select the Office Online option, you will get a similar dialogue except that you will not have to specify a server name. In case of Office Online, you will need to specify permissions. I suggest that you make the calendar available to all.

Publishing to Office Online

I recommend that you use a WebDAV server. It gives you a lot more control over the process.

Irrespective of whether you choose the WebDAV option or Office Online, you can select some Advanced Options while publishing your calendar. Here, make sure you select the "Automatic Uploads" option. Else, your calendar will be a one time upload only and that probably will not serve the purpose.

Advanced Options

You could choose to include details of Private items in your published calendar as well or simply limit it to the free-busy information. That choice is for you to make. As for the update frequency, I would suggest that you leave it checked.

Once this is done, your calendar should now be published and will be accessible for subscribers over the internet.

How does it help?

Well, just as Outlook allows you to publish your Outlook Calendar to the Internet, it also allows you to subscribe to other iCalendars that have been published on the Internet. For this, all a user needs to do is to browse to the URL where the published Outlook calendar is available. The URL will usually be in the form webcal://webdomain.com/calendar-path/calendar-name.ics.

I realized that all I had to do was to publish the calendar from one Outlook account to the internet and then subscribe to that feed from the other Outlook profile.

Let me illustrate.

If I were to have two Exchange Accounts with meetings in both of them, something as shown:

Exchange 1
Calendar in Exchange Account 1
Exchange 2
Calendar in Exchange Account 2

As you would have probably noticed, there are clashing meetings in these two calendars, which isn't very apparent when viewed in any one calendar individually.

What if I were to publish the Calendar from Exchange Account 1 and subscribe to that feed from my Outlook profile for Exchange Account 2? Here is how it would look

Exchange 2 with Exchange 1 Subscription
Exchange 1 iCalendar feed subscribed into Exchange 2

Outlook 2007 has an even cooler view — the overlay feature — which makes the clashing appointments even more evident.

Exchange 2 with Exchange 1 overlay
Exchange 1 iCalendar feed overlayed over Exchange 2

With this view, it is fairly easy to catch any conflicts you might have between the two Exchange Calendars and ensure that you don't get double booked.

Are there any issues with this approach?

Unfortunately, yes, there are:

  1. Outlook publishes the iCalendar only when the Application is running. That means that if you fail to open Outlook for one of the Profiles, your iCalendar feed will not be updated with any new meeting requests that you may have received in that account.

    Since you will probably be actively using both Exchange accounts anyway, this shouldn't be such a big problem though.

  2. Outlook may fail to download the latest iCalendar feed, which means that even though there are newer appointments in the iCalendar, Outlook will not display them to you.

    If you are using WebDAV, this can be fixed by modifying the Cache-Control on your WebDAV server to "max-age=0, no-cache, no-store, must-revalidate". This can be done either on your webserver settings or using a .htaccess file.

    The .htaccess syntax is given below:

    <FilesMatch "\.(ics)$">
    FileETag None
    <IfModule mod_headers.c>
    Header unset ETag
    Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
    Header set Pragma "no-cache"
    Header set Expires "Wed, 11 Jan 1984 05:00:00 GMT"
  3. Reminders don't work on the subscribed calendar. Hence, even when you have subscribed to your Exchange 1 calendar feed on the Exchange 2 Outlook profile, you will not receive reminders for any appointments on Exchange 1. I circumvent this by importing the feed into Google Calendar as well; Google never fails in providing reminders!

Though there still are some issues, I personally have found the above approach on the whole to be very beneficial. Let me know what you think and if you have any better ways of obtaining such a unified view of your Outlook Calendars.