Create Outlook add-ins for compose forms

You can create compose add-ins, which are Outlook add-ins activated in compose forms. In contrast with read add-ins (Outlook add-ins that are activated in read mode when a user is viewing a message or appointment), compose add-ins are available in the following user scenarios.

  • Composing a new message, meeting request, or appointment in a compose form.

  • Viewing or editing an existing appointment, or meeting item in which the user is the organizer.

  • Composing an inline response message or replying to a message in a separate compose form.

  • Editing a response (Accept, Tentative, or Decline) to a meeting request or meeting item.

  • Proposing a new time for a meeting item.

  • Forwarding or replying to a meeting request or meeting item.

In each of these scenarios, any add-in command buttons defined by the add-in are shown in compose form.

Sample add-in command buttons in compose form.

Types of add-ins available in compose mode

Compose add-ins are implemented as add-in commands. To activate add-ins for composing email or meeting responses, add-ins include a MessageComposeCommandSurface extension point element in the manifest. To activate add-ins for composing or editing appointments or meetings where the user is the organizer, add-ins include a AppointmentOrganizerCommandSurface extension point element. For more information on manifests, see Office add-in manifests.


Add-ins developed for servers or clients that don't support add-in commands use activation rules in a Rule element contained in the OfficeApp element. Unless the add-in is being specifically developed for older clients and servers, new add-ins should use add-in commands.

Add-ins that use activation rules aren't supported in an add-in that uses a Unified manifest for Microsoft 365 (preview).

API features available to compose add-ins

See also