The test email id was: DN MBSK CIT Scheduling / Planification CIT MBSK RN (IRCC) <IRCC.DNPNTCITScheduling-PlanificationCITPTNRN.IRCC@cic.gc.ca>
But inside the letter - had below text:
To contact us regarding your knowledge test and/or an accommodation request, please email: DNCITVANTESTS@cic.gc.ca