An added bonus to the big envelope is that they take priority over other mail, so the workers can hurry up and deal with your mess. If you send 2 checks they'll have to staple your unsightly envelope to your half destroyed form. Always put extra paper clips on your forms. Any foreign fasteners or the like have to be removed and put away. Sign your name in ink on every page.
Any signature has to be verified and then date stamped.
These are just a few of the fun and exciting things you can do with the man. These methods are only recommended when you owe money.