how do I list poster package shipping container from post office priority mail

Question

I am mailing a poster in a free small tube from the post office. It is 25.50 inches by 6"x6" and is stamped priority mail. Is this consider irregular mailing box. How do I make sure the buyer doesn't change the shipping service to standard shipping?

jacbarcollectibles · Answer

Yes, anything other than a rectangular or square box or a padded envelope is considered an irregular package which has an additional shipping fee. The USPS also has a fee for long packaging so this may also apply to your tube.