Delivering OnePlaceMail on the Office Add-in Framework

Office Add-ins team

OnePlaceMail is an award-winning Outlook add-in that brings SharePoint to the workplace and enables people in business to achieve more. It offers:

  • Cross-platform collaboration—Save content from Outlook to Microsoft Teams channels from any device.
  • Organizational productivity—Simplify the action of moving conversations from Outlook email to Microsoft Teams, using technology built for the modern workplace.
  • SharePoint and Office 365 Adoption—Promote the active use of SharePoint and Teams.
  • Personal productivity—Save emails and attachments to SharePoint from any device running.
  • Information and records management—Capture true and accurate records for better information management and collaboration.

Why we built on the modern Office Add-in framework

As a company, we have a long history of building Office Add-ins that build tighter integration with SharePoint and Office 365. We believe in empowering users with features and data where they need it, and in context of their normal workflow. This is why the Office Add-in platform is so powerful. The core Office applications are central to the workflow of many business processes and add-ins extend the user’s experience and deliver features and data directly in the applications they are already working in, keeping them focused and productive.

One of our existing OnePlaceMail VSTO Outlook add-in has been under active development for over 10 years. Until now, there are customers that we were never able to reach using the VSTO model. Now, using the he modern add-in platform, we can expand our reach to Outlook on the web, Mac, and mobile devices such as Android, iPhone, and iPad.

OnePlaceMail app development process

With the development of our OnePlaceMail app (modern add-in), our team didn’t attempt to take the entire feature set of our VSTO add-in and simply copy it. Rather, we looked at which features would deliver the most value to users, especially on mobile devices as we know this is where many users consume their email the majority of the time. We wanted users to act on those emails without flagging it as something to come back to when they returned to their desktop where they are running the full Outlook desktop client.

Modern web technologies

The modern add-in model based on web standard technologies allowed us to develop a single code base that would run everywhere that Outlook was available (including mobile devices). While this was a technology shift for our developers, it offered a lot of freedom to choose a technology stack to use. Our  development team was free to choose technologies like JavaScript frameworks and tooling that they already knew or were particularly suited to the add-in.

Native feel

Office UI Fabric is a great starting point for designing an add-in that feels like a natural extension of the host Office application. Truthfully, our team did run into some challenges on mobile devices where the add-ins should take on the style guidelines of the device (iOS/Android). So, if you are looking to extend your add-ins onto mobile devices, I recommend designing your add-in early to support this. Luckily, we were able to simply provide alternate CSS for the different devices.

Centralized deployment

Having come from developing VSTO add-ins, which are installed on users’ machines, our add-in really benefited from the centralized nature of the modern hosted web add-ins. With the previous VSTO model, our team would package up an installer and make it available to customers who might not install the update for months or even years. With our modern add-in hosted centrally, we had control of deploying updates and could push changes globally within minutes.

Telemetry for agile development

Another major benefit was the integration of Application Insights to add telemetry to our add-in. This allows our team to see at scale any issues or performance degradation and address issues before they are even reported. Combine this clarity provided by telemetry with the ability to deploy changes globally within minutes and it really provides a platform for a modern development life cycle where our team can iterate quickly. We’ve moved from shipping our VSTO Add-in quarterly to shipping our modern OnePlaceMail App every Tuesday!

OnePlaceMail App enables people to achieve more

The following are common scenarios where our customers benefit from OnePlaceMail:

  • Electronic Document and Records Management (EDRMS) solutions
  • Project management and team collaboration
  • Legal teams using Outlook across devices remain productive with legal matter management
  • Email management in SharePoint uses a familiar Outlook experience

Whether the solution is built on SharePoint or Office 365, the overwhelming benefit our customers see is the increased usage and adoption of their solutions.

“I’m showing OnePlaceMail to customers everywhere and they’re loving how easy it is to save to SharePoint and Teams channels from within Outlook, Outlook on the web, and the Mobile app. The mobile app really makes this solution stand out as there is nothing else out there like it!”—Sean Wallbridge

“OnePlaceMail is the tool we were looking for in our company to implement in our SharePoint solution combined with Dynamics CRM 365, delivering great value to our customers. Strongly recommend, one of the best Office add-ins.”—Rafael Belizário

“I can interact with SharePoint from the comfort of my Outlook window with OnePlaceMail. My team is collaborating and interacting much more considering important actions can be taken from Outlook directly to SharePoint without leaving the email client. Highly recommended.”—Michael Flemming

Perhaps more powerful than individual quotes from our customers is the combined voice of the public who voted us the People’s Choice winner for the best Microsoft 365 App of 2019.

Get Started with Office Add-ins

Check out the Office Add-ins developer documentation and try out the quick starts for an easy way to learn about this technology.


Author Cameron Dwyer is passionate about delivering compelling solutions on the SharePoint and Office 365 platform. He is Chief Technology Officer at OnePlace Solutions and a Microsoft MVP.

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