It’s an unethical Scam!
If you receive a letter in the mail from ‘Domain Registry of Canada’ asking you to renew/transfer your .CA domain name it is probably NOT legit! Yes, they are a legit domain registrar but they feed off of unsuspecting people by sending very official looking letters through the mail and making it look like your domain name is registered through them, indicating it is time to renew.
Domain names are rarely renewed via regular mail and usually done via email. If you receive a renewal notice from anyone named: Domain Registry of Canada, double check who your domain registrar is before sending any money. You can do this by either contacting your Web Master or checking a Whois database. The odds are good that you do not have a domain registered with them and if you do, I highly recommend you don’t partake in their unethical, albeit legal, practices.