Outlook Add-ins

What are Outlook add-ins?

Outlook Add-ins (part of the Office 365 add-in family) enable you to add new features to Microsoft Outlook. In particular they offer the ability to integrate Outlook with third party applications such as CRM systems, Scheduling systems, Email marketing systems, or any other system working with emails, contacts, or calendar events.

add-in task pane

How are add-ins different from plugins?

There are now two ways to integrate additional features with Outlook. The traditional way – Outlook Plugins (also confusingly called COM add-ins) have been around for years.

Office 365 add-ins are a relatively new method of providing additional features. Although they both provide integration options for Outlook, they are very different. So what are the advantages of each?

Add-in Advantages

  • Simple installation
  • Install once per mailbox – not per machine/client
  • Code once – use in multiple clients

Add-in Disadvantages

  • More limited user interface
  • Only work with email and calendar items (not contacts or tasks)
  • Only responds to clicks (ie not proactive – can’t respond to events)

What type of Outlook items can I work with?

Add-ins can access and interact with both emails and calendar appointments. You can not currently interact directly with contacts or tasks through add-ins (although you can with plugins and through Exchange Web Services. Call me if you want to discuss).

The area where mail-apps are accessed in Office 365

The Mail app toolbar showing above the message in office 365

What can I do with add-ins?

There are lots of things you can do with an add-in. We have taken a look at the most common things add-ins have been created to do.

Information Enhancement

This category of add-in gives the user added information when viewing emails. It typically  works based on the email address of the sender of an email. The enhanced information can be extracted from a cloud based database, such as a CRM system, order management system, Fedex package delivery, or lead scoring information system.

Calendar and Meeting Enhancement

There are lots of applications which insert details of a conference call or room booking into a meeting invite. There are also applications which help organise meeting agendas and add information to an Outlook meeting.

Filing and Document Management

Lots of systems use add-ins to aid filing – giving single click options to save emails and/or attachments to Sharepoint, CRM systems, Document management systems.

This includes saving invoices and expenses into accounting systems and similar.

CRM Interactions

CRM systems need to have acces to the interactions from customers. So add-ins for CRM providers tend to enable logging emails, creating and tracking appointments, and viewing information from the CRM when reading an email from someone. It typically combines several of the application types already covered.

Which Outlook clients will add-ins run in?

Add-ins will run in many different types of Outlook client. Traditional Outlook plugins (also confusingly called COM add-ins) will only run in desktop versions of Outlook for windows (ie the top two items on the list below).

Outlook add-ins will run in:

  • Outlook 2016 for Windows
  • Outlook 2013 for windows
  • Outlook 2016 for MAC
  • Outlook Web App (Office 365 and Outlook.com)
  • Outlook Web App (Exchange 2016 on premise)
  • Outlook Web App (Ezxchange 2103 on premise)
  • OWA for Android
  • OWA for iPhone
  • Outlook for Android (coming soon)
  • Outlook for iPhone
  • Outlook for iPad

Please note that not all features are available in all clients. For example Outlook for Mac is currently limited to only working with emails which are being read (and not emails when they are being composed).


Mail-apps can be installed by the user, or they can be managed by the Exchange / Office 365 administrator.