I am trying to configure Outlook 365 (version 16.22.1) on Mac High Sierra (10.13.6). The Mac is a domain member on a Windows Active Directory domain. Our office has a self-hosted IMAP mail server running Dovecot. Dovecot works just fine with Thunderbird and A/D authentication kerberos/GSSAPI. I'm trying to set Outlook up to use the Dovecot/IMAP server.
In Outlook, when I click 'Add Account', then enter the email address, it defaults to "Exchange". Selecting 'Not Exchange' gives me a list of other providers (Google, iCloud, etc.) and an IMAP choice. The IMAP choice only provides for ID/PW authentication, no kerberos.
Going back to Exchange (even though the server is not Exchange), I have a choice of methods, 'User name and password', 'kerberos' or 'Client Certificate Authentication'. I select kerberos. I fills in my kerberos ID which, according to Microsoft, I assume is correct. It asks me for my server which is mail.hprs.local.
I then get a pop-up saying, "Outlook was redirected to the server mail.ohprs.org to get new settings for your account firstname.lastname@example.org. Do you want to allow this server to configure your settings?" This is NOT the server I want to use to configure my settings, so I answer 'Always deny', whereupon it fails with, "Unable to connect to the server.Please try again', and no account is created.
If instead I answer, 'Always Allow', it fails with the same message.
With Thunderbird I have a manual configure page where I could set in/out servers, ports, authentication mechanism and TLS, etc. I'm not getting that far with Outlook.
Is there a way to do what I want?