After appliance is installed - on the webpage (configuration tab) there is note that users should be added by ldap, AND that administrator must login to cyrus (cyradm) to create new mailboxes.

Problem is, that it is defined that the user "cyrus" should be used, but instead, inside /etc/imapd.conf file, there is user "imap" defined as admin.

So inside web page of the appliance, please replace:

cyradm --auth plain --user cyrus localhost (login does NOT work with pass: sogo)
WITH
cyradm --auth plain --user imap localhost (login DOES work, with pass: sogo, and it is possible to create new mailboxes)

AndrijaP