A fix due in May 2026 will make sure that the Outlook classic client will handle Outlook reactions properly if the reactions are blocked. Of course, if tenants don’t like responding to email with an emoji, they can create a transport rule to insert the x-ms-reactions header. Detecting the header is an instruction to Outlook clients to suppress reactions that Outlook classic has been ignoring up to now.
Not everyone likes to respond to email with an emoji, which is why the options to disallow Outlook reactions through clients or mail flow rules exist. Everything revolves around the x-ms-reactions message header, which is what Exchange Online uses to understand if people can respond to email with emojis.
Soon after they launched Outlook Reactions in 2022, Microsoft received requests to disable the feature. Now you can by adding SMTP headers to messages. Outlook clients will be able to add the header to stop recipients reacting and organizations will be able to create mail flow rules to add the header to selected messages. It’s nice to have a way to disable reactions.
Users will soon have the option to use Outlook reactions to respond to emails received from people inside the same tenant (well, it also works with some other tenants). It’s the same kind of feature that already exists in Yammer and Teams, but whether this kind of response works with email remains to be seen. It’s a cultural thing!