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.