EXO Mailboxes on slow connections

Question

Hello,

We currently have multiple mailboxes using POP3/SMTP towards Exchange Online. Of course we have started to move away from basic authentication in general, but these mailboxes in particular are located on very slow satellite connections across the globe.

We are testing native Exchange Online connection, and that works - but causes some end user disturbances like intermittently switching to Offline and high latency when opening folders etc. We can work around this by manually pressing the "Work offline" button... and then go back online when user wants to send and receive. Requires some user training of course.

I see that Microsoft supports Oauth for POP3 and SMTP - but I have not been able to grasp if this is, or will be, supported in the Outlook client at all. Anybody can shed some light on this stupid question? :)

Other than that I am wondering if anyone has got some experience in this area and would like to share a bit. I don't expect long answers, just some quick words that I can dig deeper into.

Thanks!
Tom

Answer 1

I'm not aware of any plans to add Modern Auth support in Outlook for POP or IMAP:
https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/cannot-connect-mailbox-pop-imap-outlook

I know they have slow links, but why not use OWA or Outlook in cached mode instead of POP/IMAP?

You can set Outlook Offline as well manually.:)
https://support.microsoft.com/en-us/office/switch-from-working-offline-to-online-2460e4a8-16c7-47fc-b204-b1549275aac9#:~:text=Quick%20setup,online%20check%20box%20is%20selected.

Answer 2

Hi @jneks ,
I agree with what Andy said.

1. Microsoft announced the Exchange Online capability to use OAuth authentication for POP and IMAP and SMTP protocols. But outlook supports Modern authentication for only Exchange, Outlook.com, and Gmail at this time. If you're using POP/IMAP and SMTP for an Exchange Online account in Outlook, you must enable Basic authentication for these protocols.
2. According to the Microsoft official document, Microsoft recommend always using Cached Exchange Mode with an Office 365 account, but it should be noted that POP3 and IMPA accounts can’t use this feature. Cached Exchange Mode gives users a seamless online and offline Outlook experience by caching the user's mailbox and the Offline Address Book (OAB) locally. With Cached Exchange Mode, which is the default setting for users, Outlook no longer depends on continuous network connectivity for access to user information.
   For more information you could refer to: Plan and configure Cached Exchange Mode in Outlook

----------

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 3

Thank you for your good answers, anonymous userDavid and @Lucas Liu-MSFT !

We are testing Exchange Online cached mode and OWA in parallell - and based on your answers, and what has been our impression as well, is that we will have to guide ourselves into one of these paths (or a combination).