Office 365 – A Deeper Look at the Microsoft “Send” App

On Wednesday, Microsoft announced a new Office 365 mobile app called “Send“. The idea behind the app is to be able to send quick and simple messages to other users via email.
The first question that came to mind was, “What problem is this app trying to solve?” My phone can already send emails, IMs and text messages, did we really need another option?
My thoughts then shifted to “How does this work?”, “What kind of security options are there?” and other questions that clients are bound to ask.
In the interest of peeking behind the scenes, I ran the app through Fiddler to see what the traffic looked like. Some thoughts based on the results are below…

Getting The App

At the initial release, the app is only available on iOS and in the US and Canada. This will obviously change in the future although it’s a bit interesting to see how iOS seems to receive some of the first releases from Microsoft these days. Finding the app in the Apple App Store is a bit tricky, it’s listed under “Send, a Microsoft Garage Project“.
If you look for other “Microsoft Garage” apps, you’ll notice they have another interesting app called “Tossup” which looks to be for sending surveys to friends on where to go to for lunch, etc.

Logging In (and Out?)

The process to login to the app is pretty much the same as most Office 365 applications. I was able to easily login to the application via my organization’s AD FS. When I went to look at how to logout, I found out there isn’t a way. In the FAQ you’ll find that you basically need to uninstall the application to logout.

Sending a Message

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Sending messages is certainly quick and simple, it’s a very similar look and feel to sending a text. If the user has the “Send” app, the message will pop up in the app, otherwise the recipient will just receive the message in their mailbox. The messages are sent via your Office 365 mailbox and will show up in your “Sent Items”. Since these messages are going out your Exchange Online environment, they’ll flow through any DLP or other filtering you’re performing on SMTP traffic.

Receiving Messages

Even when you have the “Send” app installed, the messages arrive in your mailbox in addition to appearing in the app; the messages all have “#Send” in the subject line. The duplicate alerts quickly get annoying so I made a folder called “#Send History” and setup a rule in Outlook to move messages there based on that subject.
The “#Send” subject appears to be important to the app and what causes messages to pop up in the application. I was able to compose a new message with that subject line and it popped up in the recipient’s app.

The Network Trace

I configured my iPhone to run through Fiddler with SSL decryption and setup the app.
The authentication appears to use OAuth and then the rest of the app communication is connecting via an API as opposed to directly using Exchange Web Services (EWS) or ActiveSync. The API communication is all to the host “” and does not appear to be the APIs that I’ve seen published. That said, I’m by no means a developer and will probably need to have some other eyes take a look at the requests.
The “flow” name in the above hostname seems to indicate this is “Microsoft Flow” app that had information leaked back in May.

Securing Access

While the Microsoft approach seems to be allowing users to access their email from any device and any location, I have some clients that take a significantly more restrictive stance. Certainly we will be asked by clients to block access to this application and the method in which that will be done is still TBD.
Update: Exchange Server MVP Paul Cunningham found that the host application is connecting to Exchange Online via EWS and it can be blocked by using the “MicrosoftSend/*” string. Apparently when you block the app, it makes Microsoft sad.

So Do We Need This?

In the short time the app has been out, it’s amazing that people seem to be on one extreme or another with it. Some of my clients and coworkers love it right out of the gate, others think it’s an overlap of multiple existing technologies and there is no need for it.
I can see certain situations where the app could be useful. It’s definitely a bit beta but I imagine that’s to be expected out of the “Microsoft Garage”. A logout option would be nice and it doesn’t seem like you can add additional people to a group conversation that you have going.

More Info to Come

The above is all pretty early observations, more info is surely to come. Microsoft has setup a group in Yammer for the application and there is a “YamJam” scheduled on July 28th at 9:00 AM PST.
Did you find this article helpful?
Leave a comment below or follow me on Twitter (@JoePalarchio) for additional posts and information on Office 365.
Looking to do some more reading on Office 365?
Catch up on my past articles here: Joe Palarchio.

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