You can send emails to students who have not submitted the assignments through Grade Centre. 

  1. From your Blackboard course menu go to Grade Centre-Full Grade Centre.
  2. Identify the students who have not submitted  their assignments: they will have dashes in the assessment column. Select them by checking the checkboxes next to their names.
  3. Select Email Selected Users from the Email drop-down list.

selecting users

  1. Enter a subject and a message.
  2. Click on the Submit button.

message to non submitters