Recommended Clients for Exchange Activesync for Exchange 2019 Mailbox Users

Copper Contributor


In my environment, we have Exchange 2019 CU11.


My understanding from when I spoke with Microsoft Exchange Engineers on the phone was that the Outlook mobile app was built primarily around for mailbox in Exchange Online (M365). 


While I know that Outlook mobile app does have Activesync in it, the Engineers told us that for Exchange On-Premises mailboxes, we should use the Native Mail, Calendar, and Contacts apps on Android and iOS because the Outlook mobile app wasn't meant for Exchange On-Premises.


Would someone be able to confirm or give recommendations as to what is truly the way we should direct our customers to use when accessing On-Premises Exchange email on their mobile devices?

1 Reply

Hi @Craig Unterborn,

I'm agree and disagree at the same time :) 

Outlook mobile app is compatible with pure Exchange OnPrem mailboxes:


Outlook for iOS and Android | Microsoft Learn

Mobile devices | Microsoft Learn


But it's also true that there're limitations and auth concerns in such cases:



Outlook for iOS and Android in Exchange Online: FAQ | Microsoft Learn


So, basically, even if you can perfectly use Outlook Mobile App with pure Exchange On Prem server, in my case I would agree with the other engineers and use the native apps. Let's see if someone else has a different opinion ;)