We bought the best cross-cut shredder we could afford. The primary qualification was that it HAD to be able to shred a full unopened envelope of junk mail crap, WITH fake credit cards included.
We ended up with a
15-sheet cross-cut shredder (from Staples), which can also do credit cards and CD/DVD. Man, this thing is an animal, it tears up everything we throw at it. It has not met an overstuffed envelope it couldn't process.
With that shredder, I don't even open the envelopes any more. Complete waste of my time to see anything but the return address. No return address, I'll slit the envelope and glance inside to make sure it isn't something I was expecting, and then into the shredder it goes. We don't end up with a box full of "junk mail" to sit down and tediously feed the important parts through our old three-sheet strip shredder. What once was an hour long job takes minutes, and it's so easy I just drop the junk in the shredder when I come in the door with the mail.
Jim