I do many mail outs and use self- sealing envelopes. They are so easy to use. Just stuff the envelope pull off the strip on the seal and seal the envelope. Note licking or using a wet spine. Saved me lots of time when doing mass mail outs. I highly recommend you use these envelopes.
Envelopes in quality paper and very well suited for privacy. We prefer the brick and mortar Staples it is friendly and there are faces we can relate to and helpful.