Reply with IM Transfers Conversations from Outlook to Teams

Old Reply with IM Feature Works with Teams

The new Share to Teams and Share to Outlook features announced (still not generally available) by Microsoft have attracted a lot of attention, but Outlook’s Reply with IM feature seems to fly under the radar with little awareness (and no Microsoft documentation). Let’s try and redress the balance.

The idea is simple. You receive an email and instead of having endless rounds of to-and-fro replies, you take the conversation to an instant messaging platform that’s more suitable for an interactive debate. Reply with IM has been around since Outlook 2010. In those days, the IM connection was to Office Communications Server, duly replaced by Lync and then Skype for Business. Inside Office 365, depending on your configuration, Outlook ProPlus or OWA will connect to Skype for Business Online or Teams.

Reply with IM from Outlook

I used Office ProPlus Version 2002 to test Reply with IM. I doubt this feature will work with Outlook 2016 or 2019, and it seems like it didn’t work so well with earlier versions of Office ProPlus.

The Reply with IM option is found in the […] menu of Outlook’s read message window (Figure 1) or in the Respond section of the Outlook menu bar. Reply with IM launches a conversation with the sender while Reply All with IM includes all the recipients in the conversation.

Launching Reply with IM for an Outlook message
Figure 1: Launching Reply with IM for an Outlook message


To use the feature with Teams, a user must be:

  • Configured in TeamsOnly mode. The value of the registry key HKCU\Software\IM Providers\DefaultIMApp should be “Teams.” This value is set when you choose to register Teams as the chat app for Office in Teams settings (Figure 2).
  • Signed into the Teams tenant where the users you want to chat with are homed.
Making sure that Teams is registered as the chat app for Office
Figure 2: Making sure that Teams is registered as the chat app for Office

Some Gotchas with Conversation Transfer

There are some details to remember when using Reply with IM:

  • If an existing chat with the recipients exists, Teams will use that. Otherwise it creates a draft chat.
  • Teams doesn’t take the message subject and use it to name the chat, even when a new chat is created. In fact, apart from the recipients, nothing is copied from the message into the chat, so you’ll have to cut and paste information from the message body into the chat to provide a context for the conversation.
  • Federated chat isn’t supported by Reply with IM. If you use Reply All with IM and a guest user is among the message recipients, they are dropped from the conversation.
  • If one of the message recipients is blocked for chats by Teams, you won’t be able to send messages to the chat.
  • If you are signed in as a guest to a Teams tenant where an external recipient is homed, Reply with IM can launch a conversation with that person.
  • Rather bizarrely, if a shared mailbox is in message recipients, Teams includes the shared mailbox in the chat (you can clean things up by removing the shared mailbox from the chat).
  • If the message recipients contain a group, Teams drops the group when it starts the chat.

It seems like the Outlook developers might do a little work to smoothen the rough edges that Reply with IM sometimes exhibits when used with Teams, but that being said, this is a useful little-known feature that deserves more attention from users too.

It’s the detail that makes technology interesting. In this case, a feature that’s been around for a long time has a new lease of life because it bridges a gap between Teams and Outlook. Learn more in the Office 365 for IT Pros eBook, where there’s enough detail for anyone’s taste.


5 Replies to “Reply with IM Transfers Conversations from Outlook to Teams”

    1. Shouldn’t have been there… I have an article on that topic lined up, but it hasn’t appeared yet. I will update when it’s ready to go.

  1. This seems to work for me in Outlook desktop, but not Outlook online. Is there an extra setting I need to configure for it to work with the online version? The “Reply with IM” and “Reply All with IM” buttons are active in Outlook online, but nothing happens when I click them? (whereas the same buttons in Outlook desktop start a conversation in Teams, as expected.)

    1. There’s no extra setting. It’s just that the work to support an interaction between OWA and Teams isn’t fully done. I have pointed out to Microsoft that they should remove the choice from the menu…

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