While list growth is universally recognized as a cornerstone of success in email, it has also become an emotionally charged and trend-driven area of email marketing. Best practices for list growth abound, but my experience has been that what passes for best practices are generally driven by anecdotal evidence and corporate agendas more than comprehensive analysis.

In our study, we found that this lack of analysis carries over into individual marketing efforts. A frightening number of email marketers seem content to place their faith in list growth "best practices" and let their programs run on auto-pilot. While 42% actively track all sources of list growth, 45% only track some of their sources of list growth and 13% do not track any sources.  Worse still, even when sources are tracked, 32% say they rarely or never evaluate the performance of those list sources.

While it may seem obvious, not tracking and evaluating these sources is a huge mistake. Lack of consistent tracking and evaluation of sources increases the chance of wasting money on bad list sources, damaging reputation by continually mailing to bad addresses -- which adversely impacts deliverability.

Alternatively, we found that email marketers with large and thriving email databases do three things that others do not:

1)    They track all sources of list growth. Yes, tracking only some list sources is better than tracking no list sources. However, unless all sources are tracked, there is no consistent basis for comparison. Organic list growth sources, such as onsite registration, email capture through inbound call centers or at the point-of-sale for retailers, should serve as the benchmark for all other subscriber acquisition efforts. Alternative sources like sweepstakes, acquisition through social networks, co-registration, list rental, or email append, should all be held in comparison. Not only that, but tactical level tracking only serve as aggregate categories under which more granular sources (e.g., source site for co-registration) are tracked.

2)    They evaluate the performance of different sources frequently. The sole purpose of tracking sources is to enable the ongoing performance of those sources. Programs that have large and growing lists often include source performance as a key performance indicator that is reviewed at least quarterly (14% of marketers) and usually monthly (28% of marketers). This goes beyond simply looking at the number of new subscribers from a given source. Ideally, this evaluation takes ROI into consideration. But where this is difficult or sales cycles are long, engagement can serve as a good proxy for quality. What percentage of subscribers from a given source open or click an email in the first month? First 3 months? What percentage goes dormant after the first month?

3)    They diversify subscriber acquisition points.  Financial experts warn against putting all your assets in one or two investments. The same holds true when investing in your email marketing database. Put simply, the more list growth tactics that are leveraged in a program, the more subscribers the program is likely to have.
These three things go hand-in-hand. It is not a case where marketers can commit themselves to one or two of these principles and expect strong results. To accelerate list growth, email marketers need to adopt them together. Of course, Covey's famous "first things first" principle is in play. Tracking is the first step, followed by evaluation, and finally a systematic approach to adding new tactics to your arsenal.

Developing a sustainable list growth strategy is not a short-term initiative. However, we did find some basic principles consistently hold across the board. First, organic sources are the only safe bet. Start by optimizing your onsite registration process to see what messages resonate. Beyond that list growth is an ongoing practice of trial and error that should benchmark the quantity and quality of names against onsite registration. There are no shortcuts -- no matter how emphatically the expert salesperson insists his list growth tactic-du-jour is the best way to generate quick revenue. Take the input of over 350 marketers, many of whom have learned the hard way -- track, evaluate, and diversify to build our your email program's most precious asset.

If you would like to see a full copy of the study, along with a ranking of different list growth tactics, download a copy here.