In-Depth: Boosting Newsletter Sign-Ups With Our Refer a Friend Program

My partners and I have always discussed the possibility of doing some sort of referral program for Detailed Image. We have a very loyal customer base so it would only be natural to give them the ability to earn free products in exchange for referring their friends. We never could quite formulate the right way to do it, so it always sat on the backburner while we tackled other projects.

Then last year I came across an article on the Tim Ferriss blog entitled How to Gather 100,000 Emails in One Week (Includes Successful Templates, Code, Everything You Need). The post is written by Harry’s co-founder Jeff Raider and provides a detailed case study of how they executed a successful pre-launch campaign using a refer a friend program.

After sharing that article with my partners the wheels started to turn in our heads. After a few discussions we had the basic framework for what would become the Detailed Image Refer a Friend Program that we launched in early June. Overall it’s been a success for us. In this post I want to share our experiences along with some tips and tricks to add to what is covered in the Harry’s article in case you’re interested in running a similar program on your site.

The Elements of a Successful Refer a Friend Campaign

After reading the Harry’s case study, we really honed in on what elements we had to have to give us a chance at success. In our opinion, there’s no sense in doing this type of campaign unless the goal is to go big. It’s just too much work. For us, there are other more effective ways to go after our narrowly defined ideal customer, such as a professional detailer.

A referral program is about massive growth, a gigantic boost in newsletter subscribers that is difficult to achieve in any other way. The main benefit of a refer a friend program is the compounding network effect of one customer referring a bunch of friends, those friends in turn referring a bunch of their friends, those friends doing the same thing, and the whole thing snowballing into a thing of beauty rather quickly.

Once we figured that out, our parameters for success became pretty easy. The goal was to remove as many barriers as possible so that we maximized how viral the program was. Here’s what we came up with:

  1. It has to be free to participate. Requiring someone to be an existing customer is too much.
  2. Rewards have to be good, relevant, reasonably easy to achieve, and free to the recipient (no charging for shipping!)
  3. Referrals should be given an extra perk for helping out their friends, even if they don’t participate in the program themselves.
  4. Maybe most importantly, it has to be simple. Someone needs to be able to figure it out without doing much reading.

Our Campaign

We spent a lot of time working on every aspect of our Refer a Friend page. You can pretty much get the idea just by glancing at our main graphic:

DI Refer a Friend - Banner

If that catches your eye, maybe you read the next section of text:

How Does It Work?

We give you a special link to share with your friends. When your friends sign up for our newsletter using that link, you’re credited with a referral. Each referral brings you closer to earning free detailing products!

And then the rewards:

DI Refer a Friend - Rewards

The reaction we’re hoping for is “5 friends? I can do that!” And then once you get that first shipment from us, quickly and completely free of charge, you’re hooked on the program.

The Details – Removing Friction

In addition to that information page, we spent a lot of time removing friction every step of the way.

After signing up, each participant gets their own private page to help them share their unique sign-up page and check on their progress. This page we really borrowed from the Harry’s example because they did such a great job:

DI Refer a Friend Page

Their unique sign-up page to share with friends looks like this:

DI Refer a Friend - Friends Page

This is where I think this project gets really interesting. Because we’ve developed our own e-commerce platform we have the ability to relatively easily do some creative custom programming on a project like this.

You can see that when a friend signs up we send them a free shipping coupon code. After doing some analysis and projections, this is something we decided to offer to all new newsletter subscribers. If you aren’t on our newsletter and haven’t made a purchase with us, when you sign up you get an auto-generated one-time shipping code delivered right to your inbox!

We also almost entirely automated the back-end of this. Each night our system reviews referrals from the past day, checks for fraud (more on that below), credits referrals to accounts, automatically creates any reward orders, and then emails the customer:

DI Refer a Friend - Email

As far as our warehouse operations team is concerned, it’s basically a normal order for them to pack and ship, which was important to us. The system needed to be as automated as possible to minimize the strain on our team that’s already very busy in the spring.

Social Media & Text Message Sharing Links

One of the most important components of our site is it’s responsive design. Given the rapid increase in mobile traffic and purchases we’ve seen, we now are developing everything with mobile in mind. I wouldn’t say we’re quite “mobile first” yet because most purchases – especially most big purchases – still come on the desktop. It’s more like desktop is 1A and mobile is 1B. If something doesn’t work well on both, we typically won’t do it until we figure out a way to make it work.

In the case of the Refer a Friend program, it was important to get not just easy social media sharing but also easy text message sharing from the phone. If a participant views their private page on a mobile device they’ll see an additional share button for SMS text messages:

DI Refer a Friend - Mobile Page

I spent an entire day researching the best way to link these share buttons. Hopefully I can save someone some time by sharing what we found to work well for us. In each instance we wanted to pre-populate a message without pre-populating the recipients, which I learned is easier said than done. I also included the PHP function that we used to encode the URL, which varied depending upon the service.


Where URL is the URL you want to share. You cannot customize the message anymore with Facebook, however Facebook will automatically pull your title tag and META description tag from your page.

PHP encoding: urlencode

Documentation: couldn’t find it in Facebook’s documentation, but it works as outlined in this blog post


Where TEXT is the text of your tweet and URL is the URL to share. Remember to keep it under 140 characters total!

PHP encoding: urlencode

Documentation: Twitter Tweet Button



Where SUBJECT is your subject line and BODY is the body of your email.

PHP encoding: rawurlencode

Documentation: MDN

Text Message – iOS

Unfortunately iOS handles text message links differently than everyone else, so you’ll need to detect whether or not the user is on iOS before determining how to structure the link. If you’re on PHP there are libraries like Mobile_Detect that can help you do this.


Where BODY is the body of your text message.

PHP encoding: rawurlencode

Documentation: iOS Developer Library

Text Message – Android & Others


Where BODY is the body of your text message.

PHP encoding: urlencode (notice this is different from iOS)

Documentation: couldn’t find official documentation, this blog post does a good job outlining SMS links


So let’s say you’re using PHP and you want to send a text message on Android. The full HTML and PHP might look like:

<a href="sms:?body=<?php echo urlencode('Help me earn free microfiber towels and car wax at by signing up for their newsletter'); ?>">Click here to send a text message</a>

How We Promoted It

We promoted it on our site with a banner on the homepage, link in the footer, and a link in users My Account page. We sent out a newsletter. We posted it to social media, including a special Facebook Ads campaign targeted to people we thought would have a high chance in participating. We also reached out to some of our best customers who have been active in previous contests and giveaways. We’re lucky enough now to have a large enough following that if we promote something good we don’t need to do much more than this typically.

The Results

While it was relatively well embraced by our customers, we were somewhat surprised that it was almost instantly picked up by what I refer to as the “deal hunter” crowd. A few blog posts on popular “deal” sites and the thing spread like wildfire. Here’s one example from a site Heavenly Steals but there were many more. While we didn’t necessarily plan for this, the result was a huge boost in newsletter subscribers, a bunch of links to our site, more social media mentions than we’ve ever had before, and a lot of traffic to our site. Are these people the most qualified leads? No. But it’s not like we’re giving away iPads. We’re giving away detailing supplies so you’d think (or at least hope) that the majority of people participating had some interest in our products for themselves or one of their friends.

Prior to this, the majority of our newsletter signups were coming from customers during the checkout process. The only other way to sign up was by filling out the form in our footer or by visiting our newsletter page. More recently we’ve begun experimenting with pop-ups for specific visitors in certain situations, which produces more qualified leads but certainly nothing at the volume we obtained during this rush.

Here’s a graph of our non-purchase-flow newsletter subscribers since the launch of our new site in April of 2013:

DI Refer a Friend - Graph

Zoomed in a little closer:

DI Refer a Friend - Graph

That spike added 5% to our newsletter list. In one day. And we’ve been around for over 10 years! That second mini-spike was when we sent out the newsletter to our existing customers, which we delayed because of the wave of deal hunters. While much smaller, those were likely better quality referrals.

We’ve sent out a lot of rewards, although it’s certainly died down a bit from the initial rush. Many people have hit the 50 mark, with a few over 100, and our leader has over 300 referrals. The people with a lot of referrals have huge social media followings and were able to get massive results with a quick post.

I think any time you do a promotion like this, even if it’s ongoing like ours, the expectation should probably be to have one big rush. When things snowball, they really snowball. It’s tough (impossible?) to go viral again with the same deal aimed at the same audience of customers.

What About Scammers?!?!

I’m sure by now you’ve started thinking about all of the ways someone can scam a program like this. We had a lot of internal debates about whether to go through with this project, including offering free shipping to all new newsletter subscribers. Both the refer a friend and free shipping code can be abused, but we can track, quantify, and reduce abuse. Both also have huge potential upsides that we couldn’t ignore. We went through with the project knowing that we’d have to be monitoring it closely.

We used Harry’s techniques as a baseline for fraud detection, and it’s a good thing we did because when the deal hunters hit the site so did the spammers. We had a few other protections in place, but in those first few days I scrambled a bit to detect the patterns and adjust our automated and manual review processes accordingly.

This is where it’s important to have good policies in place. You can see ours on our Promo Restrictions page. If you set good strong policies you can determine whether it’s best to automate or manually enforce those policies, or selectively or universally enforce them, but by having them in place you at least have the ability to remove someone from the program when you decide they’re abusing it.

That initial rush forced us to build a more robust automated system than I had in mind, however we still do manual checks. Before any order can be shipped out someone has to manually review their referrals. There are things that a human eye can pick up when looking at a list of email addresses that are really hard for an algorithm to do.

Overall though, we’ve only had a few really bad apples. Most people submit a bunch of their own email addresses but also refer their friends, and our system is pretty good at determining which is which and only crediting them when they should be credited. Some percentage of fraud just needs to be assumed when creating a program like this. When you remove friction and make it easy to go viral, you’re also making it easier to scam.

Was It Worth It?

Absolutely! We got a ton of free publicity and it didn’t cost us anything other than our time, the products, and a tiny bit on ads. Since this wasn’t a pre-launch or one-time campaign, we now have a system in place that we’ll continue to promote to new customers and has the potential to go viral again. If that does happen, we’re prepared for it.

With that said, it was far from the best promotion we’ve ever run. It was a good tool to grow our newsletter list, the rest we’re unsure of. The long term value of the new newsletter subscribers, especially the deal hunters, is sure to be less than other newsletter subscribers.

It’s certainly something I would recommend any online business try, or really anyone trying to rapidly grow a newsletter list. Ultimately as a small e-commerce company we’re competing with the likes of Amazon and Walmart, either directly or indirectly. Any creative, low-cost, personalized, efficiently run campaign like this that differentiates us and attracts some attention is worthwhile.

2 comments on In-Depth: Boosting Newsletter Sign-Ups With Our Refer a Friend Program

  1. Rob says:

    Great work! 5% in one day is huge!

    Just thinking aloud here, but one way to potentially stop the kind of abuse where people put in their own email addresses is by not giving referral credits where referrer and referee IP addresses match. You probably already thought of this though!

    • Adam McFarland says:

      Thanks Rob! Yea we do use IP detection as one of the checks, that’s one of the best/easiest ways to detect abuse. We picked that up from the Harry’s article. We probably would have thought of it ourselves (I hope) but it was great to have their case study as a guideline for us.

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