I want my GAL on top

Suppose that you have multiple Global Address Lists in the organization. If OWA user opens address book, OWA will display Default Global Address List on top. Same behaviour applies when user selects recipients (to, cc, bcc) in a new mail item. Ever wanted your GAL to be the number one in OWA? If yes, then you are in the right place.

Please note that I don't mean allowing OWA user to view only one GAL. Mankind has already been in moon. Read KB817218 to learn how to do this.

Here is the recipe of sorting GALs in OWA:
Open adsiedit. Now navigate to CN=Configuration, CN=Services, CN=Microsoft Exchange and open properties of it. If you take a look at globalAddressList attribute, you will find all the GALs listed in alphabetical order. Now select the GAL you want to list on top and click remove. That will take GAL to "value to add" field, which is editable. From there you can take that value to clipboard and then to notepad. After removing the GAL from globalAddressList attribute click OK twice to apply the changes. Now open the same attribute again and paste the value in clipboard (or in text file) to "value to add" field. Click OK button twice to apply changes. After restarting IIS on the CAS servers, you will have GAL to be default other than Default Global Address List.

If you ever end up removing GAL without being copied by mistake, don't worry. You can always recover this value from distunguishedName property of that GAL. All you need is to navigate CN=Configuration, CN=Services, CN=Microsoft Exchange, CN=Your organization name, CN=Address Lists Container, CN=All Global Address Lists. You can find removed GAL there and copy distunguishedName property.

Once you follow above procedure, any GAL created after that time will be always default GAL in OWA. For that you may repeat same procedure to revert back your settings. Alternatively you may want to restore old default settings, then you need to remove and add back Default Global Address List as mentioned in recipe.

Bon Appetit!