These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.
The former approach to export a maildir and iterate over it with a
script broke when the mail server and the web server got on their
own hosts. This will use IMAP IDLE to check for new mails and pass
them instantly to the djange manage.py script without storing the mail
locally.
