adding email users in virtual server don't connect

Hi all,

When I add a user to my virtual server domain i created in Virtualmin via "Edit Users" and try to login in via thunderbird to test the account it will not log in saying wrong user/pass.

When I create an account (adduser xyz) from the root terminal of my vps - and added the email account in thunderbird it logs in and works fine. Am I missing some priveladge option somewhere?

I logged in as the root user into virtualmin login.

I followed this guide: https://www.virtualmin.com/node/21899

Please help. Thank you.