I recently spoke to an agent told me CIC sent me a letter 3 weeks ago requesting an additional document. I have not received it yet. She also said if by mailing does not work then CIC will probably send an email instead but I have to wait for 30 days from the date that first letter was sent.
A few weeks ago an agent told me in general CIC will determine whether to send correspondent by mail or email. CIC are absolutely mysterious, aren't they?
Best