We use these as an outside mailing envelope for contents which include a CD in a jewel case and then in a bubble mailer about 12 sheets of paper w/ information and a smaller 9 x 12 return envelope. Never had a problem sealing them until this recent batch. The seal stickiness (stickyness?) is just not there. I have to use double-sided sticky tape and it is an extra step and a hassle. Before we realized that there was a problem we got some back from the P.O. with the contents gone because they fell out. This cost us [$]postage plus the cost of the included materials. Bummer. We will probably still buy because they fit our needs as far as size is concerned but this was a bad batch for sure. Should probably return them to the store.
The only problem with these self-seal envelopes is the fact that the glue is not the strongest. Many time the envelopes become unsealed requiring tape on top of the self seal.