Encapsulation technology refers to the technique of using paper or plastic film to directly envelope and fold the accumulated inner parts and make them into deliverable products. The application principle of encapsulation technology in the field of direct mailing letters is very simple. Most of them are paper wrapping technologies. The direct mail parts that are to be packaged are no longer encased in envelopes, but are wrapped in paper and made into classes. The shape of the envelope is then cut and accumulated to complete the in-line envelope process in one go. It eliminates the manufacturing and packaging of envelopes, and effectively increases production efficiency.