Conventional wisdom tells us that 'Exchange Server' (or 'Microsoft Exchange Active Sync' / EAS) is a server-side email service from Microsoft, while 'Outlook' is a mail client. But read on ...

My primary email mailbox is hosted by Microsoft through a Microsoft 365 business subscription, and I use the Outlook Client on my Samsung S23+ Android phone (Android 14 / OneUI 6.0).

I'm struggling to get calendar and contacts sync working reliably (between the Android Calendar and Contacts apps and my Exchange account) so I've been poking around in the 'accounts' and 'sync' settings (which are handled centrally by 'settings' but also by the calendar and the contacts apps, and by the Outlook Client on the phone).

In troubleshooting 'accounts', I noticed that Android is now offering an account named 'Outlook' alongside 'EAS' (Microsoft Exchange Active Sync) as a mail server type. Further, the only way I could get 'sync' to work reliably was to enter my Exchange account as the 'Outlook' type. Here's a screenshot showing the setup: enter image description here

The left image shows the 'accounts' I have defined in settings / accounts and backup. The circled EAS account is my email account in question. The second circled account is the 'outlook' account, with the exact same identity. The middle image shows what you see as possible accounts when you choose to 'add an account' - note that 'outlook' is offered as an 'account type' alongside MS exchange active sync. And if you choose that 'outlook' account type, it prompts you for the email address (right image).

The key point being, my one mailbox has been entered as both an 'outlook' and an 'MS Exchange Server' type. The 'EAS' account was added first, but I could not get sync to work, so (for reasons unclear now, probably a suggestion by someone somewhere ...) I added the 'outlook' type, and now sync is working!

So my question is, why are there two ways to define the same account, and why would the second type be labeled 'outlook', when it's got nothing to do with outlook really - it's just an exchange server account hosted on Microsoft.

In the 'calendar' app on Android, I couldn't get sync to work when trying to sync with the EAS account, but when I told it to connect to 'outlook', it started working!

  • "In the 'calendar' app on Android", what phone model do you have as it could be a calendar app from the phnoe manufacturer? Outlook options is for email accounts from live.com, hotmail.com, etc as they all are access via outlook.com. "My primary email mailbox is hosted by Microsoft through a Microsoft 365 business subscription", You should select Microsoft 365 and select "work or school account". Commented Dec 3, 2023 at 8:43
  • @reddy Lutonadio - As stated in my post: "I use the Outlook Client on my Samsung S23+ Android phone (Android 14 / OneUI 6.0).". The calendar app is from Samsung. This calendar app displays calendar events entered locally on the phone, and also offers to 'sync' with all manner of 3rd party calendars such as google, exchange, etc. I understand that the Outlook option would suggest hotmail, live, etc - but when I entered my Office 365 account mailbox it was accepted and - that was the only way I could get calendar sync to work.
    – Steerpike
    Commented Dec 3, 2023 at 18:40

1 Answer 1


The frontend of both services for sync is probably hosted by the same server farms hence the reason the "Outlook" option works. From Microsoft's perspective in terms of design it would make sense to have one Frontend covering all the bases as it means all security and load balancing covers all clients. Easier to manage and a reduction in support teams required.

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