[Updated: We’ve corrected the reference to the portion of the business Lending Club attributes to direct mail. The company says it is not half of the business, as originally reported, and that it does not release precise data around around this, but does say that direct mail drives a “large part of the business.”]

In the sparkling popping bubbly world of marketing technology, where we’re tracking 2,300 martech companies and reporting on new and emerging technologies daily, one company raised $1.2 billion in funding, upended a very stodgy traditional market, and is now worth over $5 billion … all on the back of good old-fashioned direct snail mail.

The company is Lending Club, and I interviewed its SVP marketing, Chris Williams, on-stage today at GrowthBeat 2015.

cash“Direct mail is still a big part of our business,” he told me in a pre-session interview. “I was brought in to change that.”

LendingClub is a fintech startup that has changed the world of financing by bringing relatively ordinary people who have some extra cash together with others who need a little more cash and creating an exchange for borrowers and lenders. Think of it as an Airbnb for money: You get better interest rates when borrowing than the bank or your credit cards, and lenders get a better return on their capital.

“The idea for Lending Club came about when our CEO, Renaud LaPlanche, noticed his credit card carried a 17 percent interest rate, while his savings account at the same bank was paying 0.5 percent,” Williams said.

What the example proves, of course, is that you don’t need to necessarily be doing Snapchat Stories and WhatsApp customer support, plus implementing the latest omnichannel mass personalization marketing automation cloud solution to completely kick ass.

You just need a good idea, great execution, and the right bits of marketing technology … at the right time.

Some of the martech areas that Williams is most interested in are programmatic advertising and fractional attribution — the notoriously difficult science and art of determining which bits of marketing have accomplished which bits of success.

At our recent GrowthBeat Summit in Boston, a table full of CMOs wrestled with attribution and failed to come to a real resolution of what was working and what wasn’t. Williams acknolwedged that it’s difficult, but managed to achieve a 20-30 percent lift in conversions at a prior role, and is using the technology at LendingClub as well.

Both of those, of course, are significantly more complex and technology-dependent than direct mail.

But the lesson for marketers? What works is good.