We have been always happy with Staples where we are shopping for our office necessities. and whenever we tried to use other stores we quickly found out how wrong we were to shop anywhere besides Staples
I have found that over the last year plus that the glue on envelopes from Staples do not seal quite often. Rather then having to tape every one we started using the pre-gumed. I have noticed that you can pull them open again right after sealing. So your guess is as good as mine as to how to secure your mail.
We mail hundreds of documents and require a sturdy yet affordable envelope. We also require a pull tab seal strip. Over the years we have utilized many products however the Staples 10x13 First-Class QuickStrip Catalog Envelopes are the only ones that meet our needs. We particularly enjoy that we can order as needed and have them delivered next day at no charge. Another feature that 'seals the deal' for us is the green First Class design template. The envelope appears professional and is more highly regarded by the recipient than a plain white envelope.
The price is right the size is right but the glue is still not good. In order to insure privacy for my clients I always use Scotch tape on the closure flap. This has been a consistent complaint and Staples doesn't seem to be paying attention. Guess the only way to get their attention is to stop purchasing the item which I will do when and if I find a better product at a similar price.
The 10 x 13 envelopes with quick strip are attractive. A major fault is the very poor adhesive sticking quality. The envelopes will not seal properly. You have to add scotch tape. At least on the corners or the envelope will open prior to arriving at the desired destination. It is very disappointing that Staples keeps raising the price on these envelopes and the quality keeps decreasing. Years ago the same self sealing envelope stayed closed without adding scotch tape. It is really a disservice to Staple's customers to not fix this problem.