During the filming of writer Norman Mailer's 1970 movie Maidstone, he attacked Mailer with a hammer, and Mailer bit his ear while the cameras were rolling.
" These boxes and mailers need to be taped up so they don't open during shipping" ." To tape up" is a phrasal verb which means basically to put tape on something.
When you buy the envelope, there is already a kind of bubble wrap or padding that is part of the envelope and is used to protect what's inside the envelope or the mailer.