If IM in Outlook Web App has been enabled in your organization, you don’t have to open Lync or Skype for Business to have an IM conversation with people in your organization’s address book. You can start or accept an IM session with someone directly from Outlook Web App.
This article is for Outlook Web App, which is used by organizations that manage email servers running Exchange Server 2013 or 2010. If you're using Office 365 or Exchange Server 2016, your email program is Outlook on the web. For help with Outlook on the web, see Get help with Outlook on the web.
In a web browser, sign in to Outlook Web App using the URL provided by the person who manages email for your organization. Enter your user name and password, and then select Sign in.
Select your name at the top of the window, and select Sign in to IM.
After you’re signed in to IM, select your name again, then select your status.
Find the person you want to send an instant message to. You can look them up in People, or find a message from them and select their name to see their contact card.
Select IM on the contact card to open an IM session.
Type your message and press Enter on your keyboard.
When you’re done, select at the top of the IM window to end the conversation and close the window.
A contact might start an IM session with you. The request will appear at the top of the Outlook Web App page.
To accept the request and respond, select Accept, or click anywhere in the notification.
Select Ignore to decline the request.