Elise, 13.12.20:
I think the origin of this issue is caused by Outlook itself.Setting up a new account in Outlook, one has to provide an email address instead of a user name. With using BSD usermanager, adding a user named 'i...@mydomain.com' is converted automatically to user 'ilse'.I am not expecting that Microsoft will solve this issue on short term though.
Good old "Control Panel" -> "Mail" offers some more detailed configuration options. Just use this way to set up mail accounts instead of doing it with Outlook.
Mit freundlichen Grüßen / Kind Regards Christian Schmidt -- Signature not available.
smime.p7s
Description: S/MIME Cryptographic Signature
