I never gotten one in the mail, so I just google for them. I ended up using the first one on this page successfully: https://www.retailmenot.com/view/zulily.com. You need to spend at least $50 to qualify for the coupon though...
You can always find a coupon code for Zulily on FlashSaleMom.com, either for 10% off or $5 off. You can only use each coupon code once, but Zulily comes out with several new ones every month.
Re: Zulily coupon code?