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Microsoft 365 now has IMAP

As we shared on Reddit, we’re happy to announce the immediate availability of IMAP (and OAuth) for already supports the industry’s best email connectivity with Exchange ActiveSync (EAS), which is available on the majority of smartphones and tablets, including Windows Phone, iOS, and Android devices, as well as the Windows 8 Mail app and Outlook 2013. With today’s announcement, we now have a richer email experience across devices and apps, including those not using EAS, such as Mac Mail and Thunderbird on a Mac.


While we believe that EAS is the most robust protocol for connecting to your email, with syncing in near real time, and superior battery and network efficiency, there are still some devices and apps that haven’t made the upgrade to EAS. As an older protocol, IMAP is widely supported on feature phones and other email clients such as those on a Mac. We heard your feedback loud and clear that this was important.

In addition to offering more complete device connectivity, IMAP (along with OAuth) gives developers opportunities to build third-party clients and services that offer value-added scenarios on top of your email. We are excited to launch the first set of services today that integrate with, and look forward to sharing many more in the future.

New and unique scenarios that build on your inbox

TripIt, Sift, Slice, motley*bunch,, OtherInbox, and Context.IO have taken advantage of’s new IMAP capability and are rolling out updates today that allow their apps and services to integrate with your email. We’ll have many more to share in the near future. If you’re building an app that wants to integrate with, we’ve provided more details at the end of this post on how to get started.

Using email to improve your travel experience


With TripIt, it’s now even easier for customers to create mobile itineraries that organize travel plans in one place. TripIt can now detect emails with travel confirmations in any inbox, and automatically import them into a TripIt itinerary. It’s an effortless way to get all your travel plans organized in one place, regardless of where you book.

TripIt mobile app

Using email to improve your shopping experience


Sift makes it easier than ever to find the products you’re already interested in. It uses existing shopping content in your account to discover your favorite stores and products, then creates a personalized shopping experience. With Sift, you can shop latest sales and promotions from almost 3000 stores and browse over 2 million products from top stores, all from a personalized shopping platform.

Sift web app


Slice saves you time and money by automatically keeping track of everything you buy online, including package tracking and more. IMAP support makes the Slice experience faster and smoother than ever for customers.

Slice web app


When you shop online, motley*bunch takes your purchase emails and organizes them into a personal catalog, making it easy to track all your purchases and shipments (UPS, USPS, FedEx and more) from one convenient place. You’ll get push notifications when the status of your package changes, and by syncing your account with motley*bunch, you can search, add notes and analyze your spending–how much you spent when, where & for what–and easily share information with friends and family.

motley*bunch mobile app

More options for organizing your email and subscriptions gives customers one more way to eliminate inbox clutter, allowing you to unsubscribe from hundreds of email subscriptions.  For the ones you would like to continue receiving, you can get them all in a once-a-day newsletter. web app


OtherInbox offers a suite of tools to help keep your inbox clean and streamlined. Message Finder makes it easy to locate emails on your mobile device in a hurry, while Organizer automatically sorts your mail into folders, and the Unsubscriber tool helps you stop unwanted newsletters.

Improving the way developers build apps for email


Context.IO is a unique email API that makes it easy and fast for developers to build applications that integrate email data. With this update, Context.IO supports Learn more about it on the Context.IO blog. logo

How to connect

People use a wide variety of devices and apps to connect to their email. It’s important to support you with a great email experience across those places. Starting today, we have an even greater range of options:

EAS: for the most robust access for syncing your email, calendar and contacts. When EAS is an option, you should always choose this. To see how to setup your device, follow these steps.

IMAP: for email synchronization on feature phones, and for apps that haven’t updated to EAS, like Mac Mail Thunderbird. It’s also quite popular for value-added email experiences like the ones above.  To configure your mail client to use IMAP, use the following settings:

  • Incoming IMAP
    • Server:
    • Server port: 993
    • Encryption: SSL
  • Outgoing SMTP
    • Server:
    • Server port: 587
    • Encryption:  TLS

Mac: get more detailed instructions  here.

POP: for legacy clients that don’t support EAS or IMAP follow the instructions here.

Let us know what you think!  You can always leave comments on the blog or by using the feedback tool in the product. Just click on Feedback from the options menu in your inbox.

Steve Kafka, Principal Program Manager Lead, Protocols

Developers interested in connecting to IMAP should refer to the below technical information. 

Basics IMAP supports IMAP version 4 revision 1 as defined by RFC 3501. In particular, IMAP supports the following commands:

  • NOOP
  • ID
  • LIST
  • LSUB


Authorization for IMAP and SMTP are done via OAuth 2.0 using scopes wl.imap and wl.offline_access. After obtaining the access token from Microsoft account, your app/server passes the access token to IMAP and SMTP on login.

  • When the access token expires, your app/server must request a new access token from Microsoft account using the refresh token.
  • The access token must be used for its full lifetime before the refresh token is used to renew the access token

Both IMAP and SMTP accept a base64-encoded string as below, where {} is the user’s account, {access token} is the OAuth access token, and ^A are Ctrl-A characters (U+0001):

user={}^Aauth=Bearer {access token}^A^A

This is an XOAuth2 authentication negotiation example for IMAP.

S: 000 OK CAPABILITY completed
S: +
C: {base64-encoded string}
S: 001 OK OAuth authentication successful

This is an XOAuth2 authentication negotiation example for SMTP.

S: 220 READY
… SSL negotiation …
S: 250-BLU0-SMTP18.phx.gbl Hello []
S: 250 OK
S: 334
C: {base64-encoded string}
S: 235 2.7.0 Authentication succeeded


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