This is mainly for sellers who ship their packages in small packages and have had problems with them getting lost. My son has created an item that can be added to fishing bait to attract more fish. He gave me some samples to drop off at the post office. He is just starting out, so doesn't have much in the way of packaging supplies yet plus was trying to mail them in an inexpensive way. He had put them in regular small mailing envelopes that is used to send a note or bill payment in. He told me he' mailed about a dozen identical packages about a week before and only half had arrived at their destination. When I saw how he was mailing them, I wasn't surprised. I took them to the post office to see what would the best way to mail his items. The clerk discussed it with the branch manager and this is what they told me.
The items are about the same size and thickness as pierced earrings, with the packaging being about 3/8 inch thick. The clerk had a template to see if the envelope with the item would slide through it. The opening in the template is 1/4" thick, and you could put the envelope through it but only with a little force. Also the 3 1/2" X 6 1/2" envelope used was too small. That size envelope with thickness over the 1/4" would get stuck in the machines. The clerk was surprised the some of the packages got through. He said that, with items over the 1/4" thickness, my son needs to use at least the 6" X 9" paper envelopes. He also said the 6" X 9" paper envelope weighing 0-3 ounces would cost 98 cents to mail if shipped regular mail. The same size envelope in the vinyl bubble mailers that I use would cost $2.32 to mail if shipped regular mail.
I know this isn't the only reason packages have been getting lost, but it is something to consider when mailing those small items. My son can be independent and stubborn (like his mother), but he did go out and buy some of the larger envelopes. I suggested getting the slightly heavier kraft paper ones instead of the white paper ones to give his items a little more protection.