What mailing service should I use? We highly recommend to use one of the following mail services: USA:United States Postal Service – Certified Mail (link) Canada:Canada Post – Registered Mail (link) For an example of mailing costs, see here. Updated on November 4, 2018 Was this article helpful? Yes No Related Articles Why do I use a Certified or Registered Mail Return Receipt card? What Post Office supplies do I need to pick up? What is the recommended ordering of pages/documents in my mailing? Is it critical that the Witnesses be at the Post Office for the mailing? How many copies does each Respondent receive? Do I make copies of my documents?