How to solve the problem at the stage of connecting an account to the Amazon workmail service?

Question

Outlook

Ad+ exchange 2007 was deployed, we decided to move mail to the cloud. Amazon Workmail was chosen for the transition. Changed dns, switched, mail goes successfully, imap is ok. But when you try to connect to the service, as to exchange, when you enter your login and password, it says
"There is no connection to Microsoft Exchange. To complete the operation, a permanent or temporary Outlook connection to the server is required."
The network connection is established, the parameters are also searched, and this appears at the stage of entering the server. Tell me where to dig, can it be some kind of local cache? Because at the test stage, two machines were successfully connected, sometimes it was possible to connect to Amazon even after switching, but after killing the account and trying to connect immediately again, it can again issue it. Machines both in the domain and not. A home laptop with outlook 2013, which I previously connected to exchange via vpn, also issues it. I put outlook 2016 on a clean computer, connected successfully.

Answer 1

According to the documentation: docs.aws.amazon.com/workmail/latest/userguide/conn...
Outlook connects via the autodiscover service, so somewhere you may have a gag in this (DNS is not registered). I recommend that you use the service from MS:
https://testconnectivity.microsoft.com/
Outlook Autodiscover item.