These envelopes would not bulk feed into our printers in order to put the return address on them. I had to feed them one by one. I tried it on 3 printers too.
These security envelopes are perfect for sending checks by snail mail. Because I have several business bank accounts and for security reasons I've never banked by email or had amounts to pay such bills as utilities etc. automatically taken out of my accounts because these vary in amounts every month I would not be able to keep track of what I've spent or the balance in my account.
We use these envelopes at our church all the time. They are secure and also very easy to close. No more gross glue taste from having to lick them shut!