+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
We only changed her mailing address to the current foreign address. As a matter of fact, she is still a resident of Canada and is only abroad temporarily for personal health reasons. This temporary stay will be a bit long, hence we decided to change the mailing address so we could receive notices on time.
Actually, you should keep your Canadian mailing address because they clearly say that they only mail letters and notices to Canadian
addresses. http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=911&top=5
 
An update for all. We kept our non-Canadian (US) mailing address and we received all notifications (for test and oath) via email. Maybe US is an exception, but in our case, they did find a way to communicate with us even if our mailing address is outside of Canada.