I send the cards out through envelopes in the mail.  The services show up as 2 - 6 days for Canada, and 4 - 6 days in the USA.  In past experience, they do sometimes time a little bit longer (longest is up to 10 business days or so) to get where they're going, so please be patient.  Sometimes it's slow but it's much cheaper than small parcels that cost from 10 - 15 dollars.