If a moderator changes the role for a user send the user an information Mail (see imports/mail/AdminRegisterUserMailHandler.js) - plaintext is OK.

• If roles have changed, ask moderator if she wants to send the Mail or not?
• Consider:
  • Old role => new Role
  • Old Role => None
• Do not send a Mail,
  • if the role does not change.
  • click on "Cancel"
  • Moderator denied to send notification mails
• Mail should include
  • a Link to the meeting series
  • Old role / new role
  • Moderator that performed the change

see client/templates/meetingseries/meetingSeriesEdit.js => "submit #frmDlgEditMeetingSeries"