About: Mail Apps for Outlook

API Type:   UI Customization
API Interface: .NET
Business Logic: Adds features to standard item forms.
Development Languages: .NET
Property Access: Yes
Product Versions: 2013, 2016, Exchange Online.

 Summary

Mail Apps for Outlook development allows you to write one application which will run in Outlook desktop, OWA Web APP and OWA for Devices.  The type of development which is involved is totally different from that of Outlook Add-ins.

Points of Interest:

• There are two modes for items - one for composing new items and one for working with stored items
• The framework provides an ID for the current item and is to be used with raw EWS calls for items in compose mode. 
• There is no EWS id for compose mode and you are limited to properties supplied in the application DOM.
• The custom properties exposed are Agave properties and do not persist past the mailbox.
• In OWA customization in prior versions of Exchange a developer would create custom web forms which would be tied to a custom message class. Mail Apps by contrast allows a developer to add new features to existing forms.
• Delegate access is not supported (as of 9/20/2016).  The add-in should not be displaying in a delegate scenario.  This may or may not change in the future.

Backgrounders:

Mail apps for Outlook
https://msdn.microsoft.com/en-us/library/fp161135.aspx

Fundamental concepts for mail apps for Outlook
https://msdn.microsoft.com/en-us/library/2cd5641b-492b-4431-8388-7fc589163e9c(Office.1501401)

Requirements for running apps for Office
https://msdn.microsoft.com/en-us/library/office/dn833104.aspx

Get started creating a mail app for Outlook with Napa Office 365 Development Tools
https://msdn.microsoft.com/EN-US/library/office/jj220072.aspx

Use “Napa” Office 365 Development Tools to build apps for Office and SharePoint on the browser
https://blogs.msdn.com/b/officeapps/archive/2013/08/27/use-napa-office-365-development-tools-to-build-apps-for-office-and-sharepoint-on-the-browser.aspx

Develop apps for Office
https://msdn.microsoft.com/en-us/library/jj220077.aspx

Anatomy of apps for Office
https://blogs.msdn.com/b/officeapps/archive/2012/08/02/anatomy-of-apps-for-office.aspx

The Office 365 platform—new opportunities for developers
https://blogs.office.com/2014/03/03/create-apps-for-office-365/

Developing Apps for Office Forum
https://social.msdn.microsoft.com/Forums/office/en-US/home?forum=appsforoffice

 Exploring the JavaScript API for Office: Mail Apps
https://msdn.microsoft.com/en-us/magazine/dn201750.aspx

Top 10 scenarios for the JavaScript API for Office
https://blogs.msdn.com/b/officeapps/archive/2012/11/14/top-10-scenarios-for-the-javascript-api-for-office.aspx

 Outlook Web App Get Started
https://www.microsoft.com/en-us/download/details.aspx?id=29289

 Exchange 2013 101 Code Samples
https://code.msdn.microsoft.com/office/Exchange-2013-101-Code-3c38582c

Video Training:

 Building an Outlook Mail App using the "Napa" Office 365 Development Tools
https://channel9.msdn.com/Events/Build/2015/3-722

Building an Outlook Mail App using the "Napa" Office 365 Development Tools
https://channel9.msdn.com/Blogs/funkyonex/Building-an-Outlook-Mail-App-using-the-Napa-Office-365-Development-Tools

Channel 9 Interview: Building an Outlook Mail App using the “Napa” Office 365 Development Tools
https://officedeveloper.net/2012/09/channel-9-interview-building-an-outlook-mail-app-using-the-napa-office-365-development-tools/

Building apps for Outlook and Outlook Web App
https://channel9.msdn.com/Events/SharePoint-Conference/2012/SPC115

Modern Authentication for the Office 2013 Clients
https://channel9.msdn.com/Events/Ignite/2015/BRK3136

Also see:

About: Messaging APIs
https://blogs.msdn.com/b/webdav_101/archive/2015/08/07/about-messaging-apis.aspx 

About: VSTO for Outlook
https://blogs.msdn.microsoft.com/webdav_101/2016/08/08/about-vsto-for-outlook/