HiI take it you noticed this on ECAS? Check your spam email folder and check ECAS to make sure they have your correct email address listed. If they do and you still can't find the email from IRCC, email or call them and ask them to re-send immediately. The email contains a PDF file that is your entrance to the test and you need to print it out and take it with you for the test/interview.
I logged in to ECAS but did not find a filed where it lists my email address. However the last two emails did arrive on my email address and i checked the spam folder for the same, but did not find it. Will try to call them up as per your suggestion.