Note: Thanks to everyone who chimed in with tips in this Talk thread!
Since nobody wants to receive a box full of crumbs (well, it's probably better than coal, but still) follow these tips for shipping baked goodies.
Bar cookies and drop cookies travel best, especially in smaller sizes (higher threat of crumbification in big cookies). Try Molasses Cookies or the Classic Sugar Cookies. Avoid fragile creations, even if they look super artsy, and those that crumble easily.
Wrap each cookie, or a pair of them touching bottom-to-bottom, in waxed paper or plastic wrap. Place cookies in a sturdy box lined with extra waxed paper and fill any empty air spaces with tissue paper or newspaper. Cookie padding is KEY—they should not be rolling around and having a party in there. To maintain moisture, try throwing in a slice of fresh bread. The moisture from the bread will migrate to the cookies via cookie osmosis.
Make sure the box is packed so tight, it's hard to close. Yank out the permanent market and mark "FRAGILE" all over the box. Double-check the postage. Returning-to-sender is not a happy situation, especially with homemade cookies.
For Cakes and Cupcakes
Cakespy gave us a great idea: ship them in mason jars! Not only does it look fun but it ships safely, and if using a flat-rate box, it shouldn't be super expensive either. Read her tutorial for further instruction. Take-out containers also work well.
Be careful sending glazes on cakes though. It's best to put them in a portable container like a Ziploc baggie, then the lucky recipient can just snip the edge—instant piping bag device!
Do Not Mix All Sorts of Crazy Flavors
It's cramped in there—those baked goods have limited oxygen to share. Be careful what flavors you mix. Even if there's lots of waxed paper buffer, they will likely absorb each others' flavors. If you're shipping bacon cupcakes, for example, that smokey-scented air might infuse the gingerbread men. Just sayin.
What Kind of Boxes?
You want sturdy cardboard boxes. Uline is a great source. They are shipping supply specialists—they mean business. Try to show up to the post office with your boxes already expertly packed.
Splurge on the speedy Priority delivery. Make sure they get it within two to three days or it's not worth it. For cakes, shoot for the next day if you can.
Peruse our Holiday Sweets page for ideas. Mmm, butter...and sugar...