Redmine

I am using redmine as a helpdesk in our environment. When people send an email to helpdesk@ourcompany.com they can specify the Start Date: or Due Date: in the body of the email. However I would like to make all emails coming in through this rake task to have a default due date of the day it was entered. I tried adding the following line to my email retrieval script but it does not seem to have any effect.

due_date=$(date +%Y-%m-%d)due_date=$(date +%Y-%m-%d)

Is redmine not currently capable of this or am I missing something? I have included the whole email retrieval script below:

cd /usr/share/redmine-4.0
rake -f /usr/share/redmine-4.0/Rakefile \
redmine:email:receive_imap \
allow_override=all \
project=helpdesk \
unknown_user=accept \
no_permission_check=1 \
tracker="IT Support" \
RAILS_ENV="production" \
move_on_success=submitted \
move_on_failure=failed \
assigned_to=username \
due_date=$(date +%Y-%m-%d) \
host=mail.contoso.com \
username=helpdesk@contoso.com \
password=obscurepassword \