DavMail is a POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway allowing users to use any mail/calendar client with a MS Exchange server, even from the internet or behind a firewall through Outlook Web Access.
DAVx⁵ settings
Base URL: http(s)://davmail.server:1080/users/user@domain.tld/
User name: your ActiveDirectory account name (domain\user) or email address
Password: your ActiveDirectory password