I wrote a book called, "How to Market With Postcards".
(It's not longer on the market... you might get Alex Mandosian's version as he picked my brain to help write his book about postcards.)
I owned a lettershop, and all we did was mail postcards for the "gurus." That's how I knew Yanik and the "inner circle."
We got to see a lot of postcard campaigns... what worked and what didn't work.
With that said, the postcards that worked the best were the ones with a few bullet points and a website address. That's it. Simple. Some even sent out cards with just an web address. The response was amazing (especially if the website address had a good name like instantsalesletters.com)
And while I understand lumpy mail does well, I can mail 3 to 7 more postcards to the same person for the same cost as lumpy mail... and with a ton less hassle.
My best client sent out postcards to new brides. He got the list from magazines (women at the time spent almost $50 on various wedding magazines and my client rented these lists)... the postcards were awful (nice looking but horrible marketing)... just examples of wedding shots and dorky wedding lines as headlines (hardly any benefits)... but we sent out (if I remember correctly) more than a dozen postcards to the same person every week or so. This worked so well that my client sold the business to a syndicate of Herman's Sporting Goods (remember them) for millions of dollars -- all because of this postcard lead generation system I set up for the owner.
It worked so well that when I told my client I was getting out of the lettershop business, he BEGGED me to stay in 'til the deal completed -- the postcard marketing was that important.
Onward.
This site is one of my best-kept secrets for postcard printing and mailing:
http://www.amazingmail.comAnd these guys are great (at least they were back in the day) if you're mailing more than 1,000 postcards at a time:
http://postcardpower.comOh, and here's the best part of postcard marketing -- they're super easy to split test... try it... I did a 16-split test for a client... the winning postcard got more than triple the response compared to the worst-performing postcard. The only difference we tested was the subheadline.
Let me repeat that. If my client didn't take my suggestion and split test, he might have lost out on triple the conversions.