No. Mailing a copy of your work to yourself is not an adequate substitute for copyright registration. Sometimes called “the poor man’s copyright,” the idea that mailing a copy of a work to yourself can substitute for registration is false and potentially harmful to a copyright owner’s rights. To file an infringement lawsuit in court, you will need to produce a registration certificate. A court will not accept a sealed envelope containing the work in place of a registration certificate. A “poor man’s copyright” will not provide constructive notice to potential infringers. It will not deter potential infringers. It will not provide a basis for preventing the importation of infringing copies at the border. And it will not enable the copyright owner to recover statutory damages and attorney fees for infringement. A registration certificate is needed for these things.