E-mail rules examples

is there a template to move e-mails to junk if there is no subject,

Unfortunately there is no argument to search for an empty subject. Sorry.

But you should check with your email provider. The may have filters that can do that.

could I vary the request for rule so that rejection occurs
if not starting with letters ‘a’ or ‘b’ or ‘c’ …(etc) { ignore case}

so that I could test it/improve