Like many of you, I’ve always packaged my zines in those manila envelopes (6 x 9 inches) with the metal clasp. The lady behind the counter asked me if I knew what those clasps were for.
“I have no idea, honestly,” I said. I’d always assumed they were there so you could reuse the envelope in-house.
“They don’t do a thing for you,” she said. She then grabbed her staple remover, ripped it out, and covered the space with tape.
“Those clasps”, she said, “don’t go through a letter sorter. If you leave those on there, I have to send it as a package and charge you more. If you don’t have those, it will go through a letter sorter and I can send it as an envelope and charge you less.”
TL;DR: I was sending a single issue of a 12-sheet zine, folded in half. With the clasp, the cost was somewhere around $1.50. Without it, it was $0.70. Save money, don’t use clasps!