I think the problem is not with cyrus itself. Are u using Horde-Imp for the webmail. It is do to with the setting on the webbased mailWe use PAM and LDAP for authentication (pam_ldap from PADL). All our users are in the LDAP server but not all our users have mailboxes on the Cyrus IMAP server. Users without a Cyrus mailbox are still able to login via our Webmail service and are presented with an empty mailbox. How can I stop users without a mailbox being able to login successfully? We are running cyrus-imapd-2.1.14 and cyrus-sasl-2.1.14.
To verify you can use imtest on a non existing account
Ram