M365 Changelog: (Updated) Updated behavior for browsing large online address books

MC706449 – Updated February 8, 2024: Microsoft has updated the rollout timeline below. Thank you for your patience.

This post summarizes a change when browsing online address books in Exchange Online.  Recently, Microsoft made a change to improve performance and encourage users to use search instead of infinite browsing. This change impacts browsing in any online address list with more than 500 objects and applies to the Default Global Address List, built-in address lists, and custom address lists. The change does not affect browsing Offline Address Books.

When this will happen:

This change has started rolling and is expected to complete by mid-February 2024 (previously late January).

How this will affect your organization:

In Outlook, opening an online address book is limited to showing the first 500 users if the result set exceeds 500 objects. To find a specific user or set of users with similar names, you can use the existing search functionality in Outlook. The behavior when searching based on “All columns” is unchanged. Search continues to return results if the criteria produces a matching result set of less than 5000 objects (by checking for partial matches in DisplayName, FirstName, LastName, Alias, and CommonName). If the result set exceeds 5000 objects, no results are displayed and a message encourages you to narrow your search criteria. Searches based on “Name Only” now behave consistently with searches based on All columns. The only difference with Name Only is the criteria is naturally based only on the name value. Searches based on “Name Only” no longer allow unlimited browsing of the entire address list as they did previously.  This change does not impact browsing offline address books.

In Outlook on the web, users are already directed to use search and suggestions provided by the search engine. However, if a user selects the To: button in a draft email, they are able to view an online address list. If the online address list contains more than 500 users, no results are shown. A message directs the user to find the desired recipient using search instead. Also, the People Hub in Outlook on the web now requires a search criteria to display any users. Users automatically get a corresponding message when they navigate to view an address list.

What you need to do to prepare:

You may want to inform your end users of the new behavior. When using online address books, Microsoft recommends users rely on search. Users can enter basic search criteria (exact match not required) and view all matching results provided the matching result set is <=5000 objects.

For users that wish to continue using existing browse behavior for address books with more than 500 objects, users should use the offline address book.

Additional information