Hi Scott, Yep, you can argue until you are blue in the face with some postal workers, and they will still insist this product is a "package", and therefore non-machinable. Others will look at the average guidelines for a "letter" as listed in "3.3 Dimensions and Shape" (meaning a 6" x 9" envelope less than 1/4" thick) and therefore is machinable. Our Post Office is so small I got to know all the front desk workers my name (Kathy, Donna, Patricia & Mike), by shift, by window worked, and by preference. Which meant I _never_ mailed on Thursday. The whole problem comes down to the sorting machinery. They move envelopes at tremendous speed. As envelopes are processed, the machines will bend the envelope, sometimes as much as 15 degrees. So it must be flexible enough to bend, but stiff enough to spring back flat for the next machine to grab it. Discs themselves are flexible enough, but an envelope that is more than 1/4" thick, or has corrugated cardboard inside, is not flexible enough. Also sometimes the extra 'lumpiness' of the disc will cause an envelope to snag inside the machinery. This is hard to describe, but I'll try. Imagine the flat surface of the front of an envelope. Imagine enclosing, say, three discs in the envelope with nothing else inside. The machinery grabs the front edge of the envelope tightly. It flattens the paper of the envelope, and pulls it along at tremendous speed. Then it meets the edge of the discs. It snags on this sudden change in thickness, tears open the envelope and jams. Long story short: machine jams, postal workers cuss, your envelope gets delivered in a body bag, and there are no discs inside because they had to be broken in half just to un-jam the machine. By the way, that is the reason for "3.4.2 Disc Size and Placement". They want the disc near the top edge, because the machinery grabs the envelope at the bottom edge. They want the disc at the vertical centerline, so there is, as gradual a change in thickness as possible, when passing through the machinery. They want a gentle 'slope' to the profile of the envelope. It helps to disguise the contents of the envelope. My tricks are: 1) Put both discs into one sleeve. 2) A thin sheet of cardboard in the back ('Cardboard" is not the corrugated kind, it is paperboard - more flexible). 3) The cover letter folded into quarters in the front. 4) The disks in between letter & paperboard. This 'sandwich' makes for a more gentle 'slope' over the discs, so it is harder for the worker to feel that there are discs in the envelope. When the worker can't feel it, then the machinery won't either; and the worker will charge only machinable rates. Also, I use the larger 6" x 9" envelopes. A large envelope which is still within the size requirements of a First Class Envelope, allows for a larger piece of paperboard, and so a more gentle 'slope' to cover the thickness of the discs. Just be sure to use the brown manilla-paper type envelope. A 6" x 9" envelope falls under the regulation "3.4.3 Dimensions and Shape Standards for Automation-Compatible Enveloped Letters Containing Discs"; paragraph "f. A piece over 8 inches long (up to 9.75 inches long) must be made of paper with a minimum 80-pound basis weight or equivalent". Manilla-paper fulfills the 80-pound requirement (it is thicker, so the 'slope' is more gentle, and it is less likely to tear). One thing: don't get the envelopes with the metal clasp. They are more expensive, and they are notorious for getting caught in the machinery. Another trick is to pre-pay the postage. Yep, buy stamps ahead of time and affix First Class postage only. This is easy to calculate, since the weight of all Gutenberg packages will be the same. Some postal workers feel overworked, and don't like punching all the buttons on the computer to get the postage. If you do the postage part of the job for them, they'll let the other regulations slide (as long as the postage is correct for the weight). Just remember who does this, and go to their window always. Then give them a present for Christmas (I give home-made wine). If you have to take the political road, and engage in debate; well that is like throwing the Christians to the Lions. The trouble begins with the seeming conflicts in the postal regulations themselves. For instance "3.4.2 Disc Size and Placement" requires a maximum disc size "b. 2 mm (0.08 inch) in thickness". But then "3.4.3 Dimensions and Shape Standards for Automation-CompatibleEnveloped Letters Containing Discs" requires a maximum envelope size "c. Thickness, not more than 0.25 inch or less than 0.009 inch thick". So any time a postal worker wants to be a pain in the ass, they can quote 3.4.2 and say two discs in one envelope are bigger than regulation. And they will charge non-machinable. That is simply a lie. 3.4.2 refers to the thickness of a _single_ disc -- not a package of multiple discs. For a package of multiple discs, the worker should refer to 3.4.3. But as we all know, if the postal worker had a spat with their significant other before coming to work, they will charge non-machinable. And there is nothing short of a lawsuit that will change their mind. Maybe not even then. I hope the above suggestions will help, Jay Toser