In my last post When should I choose to create a mail app versus an add-in for Outlook?, I provided some factors for you to consider if you’re trying to decide whether a mail app or add-in is more appropriate for your Outlook extension scenario. Along with that post are a couple of object model maps to illustrate the supporting JavaScript API for Office. On February 27, we released a major new update to the Office 365 services for business. This update to Office 365 includes a new set of API for mail apps to access mail attachments, and hence the object model maps have been updated on that post. At this point, this new feature is available to mail apps running on Outlook Web App accessing mailboxes on only Exchange Online. This new feature offers a mail app the capability to send a third-party web service an authentication token and attachment identifier, so that the web service can retrieve the attachment from the Exchange Online server. If the user’s mailbox is hosted on Exchange Online, then the user can install and start such a mail app on Outlook Web App that uses this new set of API to access mail attachments.

The following is the set of new APIs that support accessing attachments:

In the next few weeks, there will be additional content and example elaborating how to use these new objects and members. Stay tuned on the Apps for Office and SharePoint Blog for the latest news!