I am trying to build a new add-in command (button) to add to the Home tab in the Outlook ribbon. This is easy enough to do, but my organization also wants to target the button based on properties in one's Active Directory profile (specifically department). Is this possible? Thank you so much!
This is pretty straightforward with desktop office add-ins (like VSTO). All you need to do is basically to get information about the currently logged in user organizational unit from the active directory, and then show/hide/modify buttons depending on this information.
From the tags on your question, it looks like this is NOT what you are looking for (please correct me if I am wrong)? The fact that you added "office365", probably means that you are interested in javascript (cloud/browser/store) solution?
For javascript-based add-ins, the part where you get the user department from its profile was impossible until recently. Now you may check out the Single-Sign-On API (added last year). It provides you information from user's Azure active directory profile, meaning that your organization is supposed to be part of it. Another difficulty could be, dynamic display of the related buttons (showing/hiding/enabling/disabling) (I may be wrong, but it looks like it is still not supported for javascript). You can try to create a workaround for that by building a custom task pane instead (you can do whatever you want on your task pane)
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In case of .NET VSTO add-in, you can get user groups using:
UserPrincipal.Current.GetAuthorizationGroups()
Then you can control which buttons/controls to show/hide by providing callback function(s) in your code and in your ribbon interface definition file (you need to define Ribbon using XML, not with UI designer). There are callbacks available like getVisible, getLabel, etc.