Redmine

HI all, i'm using redmine version 4.2.3 with this cron for create ticket when i receive an email:

cd /usr/src/redmine/
rake redmine:email:receive_imap \
RAILS_ENV=production \
host=mail.mydomain.it port=993 ssl=true \
username=email@mydomain.it password="password" \
move_on_success=INBOX.redmineseen move_on_failure=INBOX.redminefailed \
project=assistenza tracker=support \
unknown_user=accept no_permission_check=1 \
default_group=segnalatore 

How can I use my redmine to send an automatic reply email when the ticket is created? Even to an unknown user?
I've also tried "create" instead of "accept" but nothing...
thank you