Below are 12 proven tactics for growing your email house list.

These tips come from yours truly, who has built this list over 13 years, and from Managing Editor Eileen Shulock, who is also the e-commerce director at Intermix, a fashion-forward retailer with 24 stores across the US.

Here are my 6 tips...

1. The Power of Pass-Along:

The first resource to consider when growing your list is your existing subscribers. Nothing is as powerful as an existing subscriber forwarding your mailing to another person. It's a form of endorsement.

Of course, the content of that email newsletter or the value of your offers has to be top notch for someone to forward your message to another. Typically, Web Digest For Marketers gets the most new subscribers on the day it is published. If the issue is a home run, we get an unusually large number of new subscribers.

2. Offer a Premium:

Web Digest For Marketers is a free email newsletter, but new subscribers still get a premium for subscribing to it. The premium is my "Essential Search Engine Marketing Resource Guide." Tens of thousands of people have clicked on the link for that offer in the welcome message and downloaded that guide.

Hint: Consider how short or long to make your downloadable premium. If it is too short, it may not have enough content in it to make it attractive. If it is too long, people may not want to read it. Longer is not always better.

3. Put Your Subscription Form Prominently on Your Home Page:

Amazingly, I often see subscription forms buried deep inside websites or way down at the bottom of home pages where people are less likely to find them.

People may never come back to your site. But if they subscribe to your house list, you can reach out to them. If they leave your site without subscribing, never to return, you've lost them forever.

4. Experiment with Co-Registration Programs:

This gambit often requires that you cooperate with competitors, which is sometimes called "coopetition." After someone has subscribed to your list, you offer that new subscriber the opportunity to subscribe to someone else's list.

On this "co-reg" page you might use language like "Here are some other newsletters (if that's what they are) you might find useful." If you out-and-out endorse the other lists, the subscription rates to your co-reg partners' lists will typically be higher. You want that because such arrangements typically are reciprocal, whereby you send your competitors as many subscribers as they send you.

This co-registration tactic is one of the most overlooked opportunities online. It amazes me how many subscription processes end up on a page that merely says "Thank You for Subscribing" and that's it. No other offers, or even a link back to the home page. They just leave you hanging there.

5. Offer an Event Registration Subscription Option:

If you promote a Webinar for which online registration is required, consider adding a checkbox to that reg form asking if the registrant wants to subscribe to your newsletter, or update list or what have you.

Don't just simply ask if they want to be signed up. Tell them exactly what value they will get from doing so. Keep it short. Always have a short block of copy (30-40 words) ready to slug in for such occasions. I've found it is worthwhile to write such copy long in advance, rather than at the last minute. Remember, the shorter the copy block, the more likely they'll read it, but the harder it is to write because every single word must work hard.

6. Buy Subscribers:

You must know how much each subscriber is worth to you before you lay out money to grow your list. You may pay as little as 40 cents for a subscriber or as much as $10, depending on whether you are B2B or B2C and what industry you're in. Generally you get what you pay for, but you can easily overpay, too.

If you buy subscribers, you must find out where these subscribers are coming from. Subscriber or sales lead brokers don't typically like to tell you this because they're afraid (with good reason, btw) that people will go directly to the source and cut them out. They're apt to tell you your offer will run on a "blind network." Nevertheless, you need to have a realistic idea of where your offer is running.

Recently a list broker offered me an interesting opportunity. They were making phone calls trying to win back subscribers to a print publication in the ad business. Whether they got the old subscriber to subscribe again to this print publication or not, they would offer a free subscription to my newsletter at the end of the call. I would pay them for each subscription generated for me.

7. Collect Addresses at Points of Sale:

If you have physical stores, ask customers if they'd like to sign up for your email house list at the point of sale. It is important to be very clear about what the customer can expect to see from you in the future, as required by CAN-SPAM law.

Many stores have not yet perfected the process for gathering email sign-ups in store. Recently I made a purchase in a store where at the point of checkout I was asked to type in my email address and check a box consenting to receive emails from the company. It was multichannel marketing nirvana.

In a real-world Intermix store, the salesperson asks the customer for her email address and types it in during the checkout process. That works, but it doesn't always work out so well because there are often typos or bad formatting of email addresses.

Finally, no store that I have ever visited has asked me for an email address when I am browsing, as opposed to actively purchasing an item. But many times when I am browsing I have an active interest in the store and would like to get on a list, I just am not purchasing at that particular time. In the near future, look for us to feature places in store where browsers can sign up for our email list.

8. Work Proactively with Promotional Partners:

Some of my most successful email sign-up campaigns are partnerships wherein a gift certificate or other prize is offered on a partner site. The money for the gift certificate is the cost of doing business – these are not advertising campaigns. They are a way for complimentary sites (such as magazines or blogs) to offer a perk to their readers.

If the partner is closely aligned (which is rather obvious but worth mentioning), I have experienced up to a five-fold increase in subscriber rates during the run of the campaign.

9. Offer Major Incentives to Key Active Subscribers:

We often offer deals to our key subscribers – in our case, our top customers – that we hope are so juicy they cannot help themselves but to forward the offer along. One example of this in the retail business is called the "Friends and Family" offer, where a discount or other incentive is sent to special people and they are asked to forward the offer along to their friends and family.

Another way that we accomplish this is to send a survey invitation out to key subscribers that gives them a discount on their next purchase in exchange for a completed survey. At the end of the survey they get a special code, and the offer to immediately forward the same survey invitation to their friends. Not only do we get more subscribers, we also get more responses for our survey. You can track this type of campaign easily with the features found in an inexpensive survey tool such as SurveyMonkey.

10. Forward to a Friend:

If you have the technology to truly track a subscriber's "forward to a friend" actions, you can zero in on subscribers who do a lot of forwarding and incent them to do even more.

To really make this pay off, you need to be able to:
1) See how many invitations a particular subscriber sent, and to which email addresses;
2) Track those forwards to see who actually signed up for your list as a result of their invitation; and
3) Be able to then associate new subscribers back to the individual who invited them, so you can pinpoint who your successful forwarders are.

If you can do all of that (ask your IT team or ESP if you actually have this capability) you can then incent or reward the subscribers who forward to do even more for you.

11. Test Your Subscriber Sign-Up Incentive:

We frequently change our subscriber sign-up incentive to see which offer subscribers respond to better, and which offer results in more profitable subscribers.

For example, we tend to get better, more relevant new subscribers when we offer incentives that focus on giving them a discount on their first purchase. This means that the people who subscribe are actually interested in purchasing from us, which is of course important to us, so we are willing to offer a sizable, more "juicy" incentive that is really hard to resist.

In contrast, we find that offering something that's not as juicy doesn't draw as well, and draws less relevant subscribers. So we are willing to give away the big bucks to build our list aggressively.

12. Offer Your List in Different Formats:

These days we see a growing number of people subscribing to our list with BlackBerry extensions on their email address. Through surveys we have learned that many of our subscribers read their emails from us on PDAs or iPhones.

Therefore, we are now offering our email newsletter in different formats optimized specifically for these various devices. This allows the potential subscriber to choose a format that is relevant for him or her, rather than passing on a subscription because the only format offered assumes he or she will be sitting at a desktop when reading our emails.

Attention Bloggers and Twitterers: You can link to the contents of this newsletter at the following URL and know it will live there permanently:
http://www.wdfm.com/marketing-viewpoints/grow-your-list.php