On any email list, there will be subscribers who signed up and never again showed signs of life.

They may have opted in to a specific offer, then disengaged once they obtained the coupon, free content, or other benefit you promised. Or they joined your list while in the market for your product or service but soon afterward their needs were met and they never bothered to unsubscribe.

In email lingo, we call such list members "inactives." The reality is that unless inactive subscribers specifically tell you why they haven't responded, you really never know for sure. Is it because they...

• Are not the right fit for your product or service?
• Were once a fit but aren't anymore?
• Are no longer interested but haven't unsubscribed because they're "hanging in there," hoping for improved relevance?
• Became overwhelmed and disengaged with email as a communication channel?
• Are angry and upset because of a bad customer experience?

Any of those could be the reason.

You'll likely never really know on an individual basis, but it's safe to assume that at least some inactive subscribers would like to re-engage. They just need a good reason for doing so and, possibly, would like to do so in a channel other than email.

Because of that, here's my recommended four-step course of action for dealing with inactives.

1. Conduct a reactivation email campaign

Identify inactives on your list according to agreed-upon criteria (Never purchased? No clicks in 12 weeks? Zero opens in six months?), and segment them for a reactivation email campaign containing a special incentive if they opt in to your list again, confirm permission, or provide expanded information.

2. Connect via social media

New (and dare I say it, way cool) low-cost applications such as Flowtown make it possible for you to identify which social-media networks your email-list members belong to on a person-by-person basis.

Reach out to them to friend, link to, or follow on Facebook, LinkedIn, MySpace, Flickr, Twitter, and more.

If you can get an active connection going in a social-media environment, chances are the next time your email message arrives, that list member will pay more attention to it.

3. Attempt offline connections

If establishing contact online doesn't work, try connecting via direct mail or telephone to reconfirm and refresh email-list sign-up.

Outreach through offline channels adds variety to your marketing mix and stands out; those who might be ignoring their inboxes or those who simply might have changed email addresses and need to provide you with the newest, most-relevant one, might well appreciate the contact.

4. Reduce volume of email messages sent or suppress entirely

Less-active email-list members warrant less-frequent communication. Suppress inactives from all but your most-general email campaigns (such as your newsletter or quarterly updates), or suppress them entirely.

You don't need to wipe them off your list, simply don't email them as much , unless and until they show an increase in responsiveness.

Suppressing inactives that you have failed to re-engage via reactivation campaigns will boost your email-campaign performance metrics considerably. Remember, large list size is meaningless if a sizable percentage of list members aren't engaged.

* * *

Email-list management and maintenance should be a living process, never an afterthought. By monitoring your subscriber engagement, you'll undoubtedly identify inactive segments and be able to deploy the strategies described in this article.

On the flip side, you'll also identify your most-engaged members, so don't ignore them! They deserve segmentation for special—albeit different—treatment, too, because you'll want to do all you can to remain in their inner circle for the long term.

Perhaps the most-valuable outcome of good subscriber-engagement practices is adopting a "quality over quantity" mindset. Numbers are important, sure, but only to a point. Small, highly targeted lists with highly engaged and loyal list members outperform sheer volume almost every time.