By Loren McDonald, Vice President of Industry Relations

Many email marketers (and a lot more CFOs) think if a little email is good, a lot more is even better. It's an easy assumption to make. If a campaign or program does great business once, it will the second, third and fourth time, right? Certainly, that's what your boss thinks, especially during high-volume retail seasons such as Christmas, Mother's Day and back-to-school. But it just isn't necessarily true.

Remember that email is different from other marketing channels. Optimum frequency isn't just the number of "drops" you want or need to make to reach your ROI goals or your quarterly revenue projections. It's also how often your subscribers want to hear from you.

Yes, in the short run, doubling your weekly mailings from one to two might give you a decent lift on the bottom line. But, stop right there. Over-mailing has long-term risks that can not only wipe out your short-term gain, but also leave your program in the hole.

On the other hand, not mailing often enough may hurt your email program in the long run as well.

So, not surprisingly, "What is the optimum frequency?" is one question I hear all the time from email marketers. Problem is that it’s the wrong question. Instead, ask this: "How can I create an email program that uses demographics, preferences and behaviors to maximize my customers' lifetime value?"

The real costs of over-mailing
While moving to a higher frequency can deliver increased revenue in the short term, it may actually end up costing you money over the longer term. Here's what can happen:

• You lose subscribers by annoying them to the point that they click the spam button, unsubscribe or simply delete your emails unopened.
• Your churn rate then climbs significantly, requiring you to spend more money to replace these lost subscribers. And you've lost any potential revenue from these fallen-away customers.
• Increased frequency may raise spam complaint rates above certain ISPs thresholds, getting your messages blocked or filtered and reducing your overall delivery rate–costing you direct revenue.

Detecting subscriber discontent
How do you know if you are over-mailing? Track not only process metrics like click-through, bounce, unsubscribe and spam complaint rates but also strategic metrics–total revenue per campaign, average revenue per email, average revenue per order–over several campaigns. In particular, compare different time periods during which you sent emails with greater and less frequency. Look for spikes in unsubscribes and spam complaints and corresponding drops in opens or click-throughs.

Monitor your feedback and reply-to addresses for subscriber comments and analyze the rate of frequency and channel preference changes (if you offer options). Conduct regular subscriber surveys to obtain direct feedback.

Under-mailing can hurt, too
Most frequency discussions warn you not to send too much email, but sending too little email can also cripple your marketing program.
 
Email is a digital, immediate medium. Subscribers forget about you if you wait too long to start sending email or send infrequently. Quarterly mailings are for paper newsletters. Email newsletters should generally go out at least monthly.

Additionally, what is too frequent for some subscribers might be too infrequent for others. Offering subscribers frequency choices, such as monthly, twice monthly, weekly or "whenever we have an offer," means that the optimum conversion and frequency combination might be once a month for one segment and 15 times a month for another.

Why customization and relevancy impact frequency 
The right frequency is both unique to the recipient, but also directly driven by the relevance and value of the emails. "Batch and blast" emails sent twice a week might be spam-complaint material for a subscriber, but twice-weekly emails based on preferences and behavioral data, for example, might be the perfect cadence for the same person.

The first thing to do to move your program forward is to create a customer preference center if you don't have one, or promote the one you have. This lets subscribers set the frequency, format and content they want. Then make sure you deliver on those expectations.

Better yet, move to a lifecycle, behavior- or trigger-based approach. This method changes the, "What's the right frequency?" question to, "When do I send emails to optimize the value and relationship of each segment?" And because many of these messages can be triggered by customer activity, once set up your program can almost run on autopilot.
 
When you build your program around your subscribers, their preferences and behaviors drive the optimum frequency and your program success.