Can't send email with Bulk Operation?
Just given it a quick test with VBO 1.10, and as you said, emails are not being sent. Also, got "Cannot use %author token in this context." error in log.

See this issue - http://drupal.org/node/1003354 - "Can't sent email (or 'send tokenized email') on a user view. Reverting to 6.x-1.9 works" - seems that 1.9 should work better, or - if dev is acceptable to you - 6.x-1.x-dev

Or use Views Send instead (http://drupal.org/project/views_send)