mass_contact.permissions.yml

mass contact administer:
  title: 'Administer mass contact'
  description: 'Allows the user to add, change, & delete categories and to change the administrative settings of Mass Contact.'
mass contact include attachments:
  title: 'Attach files to messages'
  description: 'Allows the message sender to include attachments with the message.'
mass contact change default sender information:
  title: 'Change default sender information'
  description: 'Allows the message sender to change the default sender name and email address.'
mass contact override archiving:
  title: 'Override message archival setting'
  description: 'Allows the message sender to override the "Archive messages by saving a copy as a node" administrative setting when creating the message.'
mass contact override bcc:
  title: 'Override BCC setting'
  description: 'Allows the message sender to override the "Send as BCC (hide recipients) by default" administrative setting when creating the message.'
mass contact override text format:
  title: 'Override default text format'
  description: "Allows the message sender to override the message body's default text format when creating the message."
mass contact send messages:
  title: 'Send messages with Mass Contact'
  description: 'Allows the user to send messages with the Mass Contact.'
mass contact view archived messages:
  title: 'View archived Mass Contact messages'
  description: 'Allows viewing of archived messages.'

permission_callbacks:
  - \Drupal\mass_contact\Permissions::categoryPermissions