I have this problem with some mailboxes (actually Maildirs) on my system. After some user's activity there is following information in dovecot logs:
Jan 29 16:24:28 mailserv dovecot: IMAP(username): unlink(/var/spool/mail/imap/user/username/Maildir/cur/Sent:2,ST) failed: Is a directory
User can not connect to his account neither via POP3 nor IMAP. There is one workaround I know which is:
rm /var/spool/mail/imap/user/username/Maildir/dovecot.index*
But after some time (some activity of user) the problem comes back.
Mikie
Please post the configuration of dovecot (dovecot -n) for more information of your problem.
# 1.0.15: /etc/dovecot/dovecot.conf log_path: /var/log/dovecot.log info_log_path: /var/log/dovecot-info.log log_timestamp: %Y-%m-%d %H:%M:%S protocols: imap imaps pop3 pop3s ssl_cert_file: /etc/apache2/ssl/server.crt ssl_key_file: /etc/apache2/ssl/server.key disable_plaintext_auth: no login_dir: /var/run/dovecot/login login_executable(default): /usr/lib/dovecot/imap-login login_executable(imap): /usr/lib/dovecot/imap-login login_executable(pop3): /usr/lib/dovecot/pop3-login first_valid_uid: 100 first_valid_gid: 100 default_mail_env: maildir:%h mail_location: maildir:%h mail_debug: yes mail_executable(default): /usr/lib/dovecot/imap mail_executable(imap): /usr/lib/dovecot/imap mail_executable(pop3): /usr/lib/dovecot/pop3 mail_plugin_dir(default): /usr/lib/dovecot/modules/imap mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap mail_plugin_dir(pop3): /usr/lib/dovecot/modules/pop3 pop3_uidl_format(default): pop3_uidl_format(imap): pop3_uidl_format(pop3): %f auth default_with_listener: mechanisms: plain login verbose: yes passdb: driver: sql args: /etc/dovecot/dovecot-sql.conf userdb: driver: sql args: /etc/dovecot/dovecot-sql.conf socket: type: listen client: path: /var/spool/postfix/private/auth mode: 432 user: postfix group: postfix master: path: /var/run/dovecot-auth-master mode: 384 user: mailsystem auth default: user: mailsystem verbose: yes passdb: driver: sql args: /etc/dovecot/dovecot-sql.conf userdb: driver: sql args: /etc/dovecot/dovecot-sql.conf