The function will initially be available in the web version of Outlook, but will later also be introduced in the client versions for Windows, Mac, IOS and Android. However, the client versions will only get the function in the middle of next year.
In addition to the like button, Outlook will also get a function called @Mentions that allows you to tag other users in an email. By tagging a user in an email, Microsoft believes that person shows greater attention to the message.
The new social features will only work for those using Office 365 Business, Enterprise and Education. It is not clear whether the consumer versions of Office 365 will also be included in the future.