Redmine

It happens that for certain html email, rake create an emtpy ticket and Description is (unsupported).
Here below my Redmine environment:

Environment:
Redmine version 3.3.1.stable
Ruby version 2.3.1-p112 (2016-04-26) [x86_64-linux]
Rails version 4.2.7.1
Environment production
Database adapter Mysql2
SCM:
Git 1.7.10.4
Filesystem
Redmine plugins:
no plugin installed

Rake configured:

rake -f /opt/redmine/Rakefile redmine:email:receive_imap RAILS_ENV="production" host=xxxxxxx username=xxxxxx password=xxxxx project=xxxx allow_override=project,status move_on_success=Processate move_on_failure=Non_processate unknown_user=create no_permission_check=1 --trace >>/var/www/www-ticket-it/logs-redmine/redmine-dbook.log 2>&1;

Could you please helpl me?