[Dovecot] Non-atomic Flags in APPEND

I'm using Evolution and Dovecot (on the localhost) and receiving these errors trying to move a message into the IMAP folder:

C00095 APPEND INBOX (\Answered \Seen NotJunk "Junk" "NotJunk" "receipt-handled") {1022} C00095 BAD Error in IMAP command APPEND: Flags list contains non-atoms.

Is this a Dovecot or Evolution bug?

Thanks, Richard

$ dovecot -n # 1.1.11: /etc/dovecot/dovecot.conf # OS: Linux 2.6.28-11-generic i686 Ubuntu 9.04 log_timestamp: %Y-%m-%d %H:%M:%S login_dir: /var/run/dovecot/login login_executable: /usr/lib/dovecot/imap-login mail_privileged_group: mail mail_location: mbox:~/Private/mail auth default: passdb: driver: pam userdb: driver: passwd