It’s been said before and it bears repeating; when it comes to those traditional three pillars of direct response marketing “the gold is in your list”.  So, it pays to treat it like the treasure it is.

In Part 1 of this series I explored ways to attract new prospects to your list.  Still, the reality for many marketers and business owners is that the majority of their email list subscribers are customers, not prospects.  They are people with whom we have an existing (and hopefully, positive) business relationship.  All the more reason to protect your treasure.

Yet that Achilles heel of email customer lists remains: it seems impossible to get the email addresses for 100% of your customers.  With few exceptions, (say, you sell only online and email address is required on every sale) some customers are just never going to hand over their closely guarded email address (or the specific address you want).  Others now prefer to communicate with you on social media (largely Facebook and Twitter).  Still more are happy to stay old school – they want phone and direct mail communication.  Send ‘em their catalogs and coupons and they’re content.

Even though 100% coverage of customer email addresses might be unrealistic, we can certainly shoot for the high double digits; certainly upwards of 60%.  And the good news is that acquiring the email addresses of customers – an audience that already knows and is engaged with you – is a lot easier than obtaining email addresses from prospects, who may be neither interested nor engaged.

Here four customer email address acquisition tactics you should put in place (if they’re not already) to immediately grow your customer email list and with it, your customer relationships:

1. Give to receive
There’s no faster way to gather email addresses than requiring them for access to online content and information, especially when email is needed to send people registration confirmations or notices of availability.  Offer your customers something exclusive; give them access to video, audio, interactivity, tools, widgets or even written material that prospects don’t get.  Be prepared to give in order to receive.  This tactic can work particularly well with those customers who were once email subscribers but left your list.

2. Leave no “offline stone” unturned
Sure it’s easiest if people buy or subscribe online because we capture the email address right from the start.  But let’s face it – almost all of us have an offline dimension to our business, or legacy business channels (like catalog) that were alive and well before the Internet bloomed.  Use those offline touchpoints to ask for the email address – and explain what’s in it for your customers to give it up – at every turn.  In a retail environment, train your store clerks to ask for it at the point of sale.  In bills, catalogs and on postcards provide BRCs or links that go directly to email sign-up pages.  Train anyone talking to customers by phone to ask them for the email address in conversation too (just make sure they can answer the “why do you want it” and “what’s in it for me?” questions).  There is absolutely not one single point of offline contact that cannot be leveraged to at least attempt to gather an email address.   More often than not, you’ll successfully get it.

3. Offer a reward
Remember tactic #1 above? This is similar.  Ask your customers for their email address (and asking for additional data valuable to your marketing never hurts either) and reward them with an entry into a sweepstakes or prize drawing.  Just be careful how you promote it – if it’s exclusively customers who are eligible for the reward, you’ll need to be specific on that point when you promote the contest on your social media or site pages.  On the other hand, if your sweeps is open to either customers and prospects, have at it, but remember many prospects who willingly provide an email address may not remain on your list long (they’ll sign up for the chance to win a prize, then possibly bail).  Make sure customers know about the promotion by reaching them through offline channels especially.

4. Expand sign-up and registration beyond your domain
Believe it or not, sometimes your customers don’t know HOW to join your email list.  Are you making it easy for them? If your primary Web site or online store isn’t, add a one-field email list sign-up form to your home page.  Then add a link to it from within your social media pages or blog.  Extend automated email list sign-up into physical store environments via kiosks or terminals; extend it into the mobile environment with an app.  At speaking gigs or events, gather business cards or use sign-up forms.

Growing coverage of email addresses on your customer list is a marathon, not a sprint.  But if you train well and keep at it, you’ll reap the rewards of being able to go the distance.

Still, as I warned in Part 1 of this series, quantity alone is meaningless.  100% coverage of customer email addresses won’t help you if no one’s interacting with your messages.  Tune into the third and final article in this series next month for the secrets to creating an email list of responsive subscribers who don’t just stick around, they engage.