Newsletter Referral Incentive

Has anyone created a referral incentive for your email newsletter signups? If so, what incentive did you use and how successful would you say that approach was?

I got the idea from my day job where we have an employee referral program—if a current employee refers someone who ultimately gets hired, the current employee gets a $200 bonus. So I thought, why not offer something similar for email subscribers? If a current subscriber gets someone else to sign up, they can just pass on the new person’s name/email address and then I give the referring subscriber a thank you gift. I’m thinking the thank you gift will be a short story or some behind-the-scenes PDF from my reader magnet.

Any ideas, cautions, or experiences you’d like to share? Thanks!