The servicer must send you a written notice of the action it took and why, as well as the name and phone number of someone to contact. (consumer.ftc.gov)
If you are filing a contested divorce, your spouse has the right to formal notice of the action. (mediationadvantage.com)
The February 5, 2009 Order of Master Breitkreuz from Knott v. Sutherland says that the plaintiffs could substitutionally serve one of the multiple defendants by publication of a notice in the newspaper, by forwarding a copy of the statement of claim to the human resources department where the defendant (formerly) worked, and also by sending notice of the action to the Facebook profile of the defendant. (slaw.ca)