Is Thunderbird supposed to show alerts sent via post-login scripts as in the wiki example?

dovecot-imapd 1.0.5-1 (Debian) Thunderbird (Icedove) 2.0.0.4 (Debian)

# dovecot -n|grep 'mail_executable(imap)' mail_executable(imap): /usr/local/sbin/dovecot-alert.sh

# cat /usr/local/sbin/dovecot-alert.sh #!/bin/sh

echo "* OK [ALERT] Hello World." exec /usr/lib/dovecot/imap

Logging in with Thunderbird I get this alert: "Mail server imap.example.org is not an IMAP4 server".

-- Thank you, Marco De Benedetto