The question among many attendees was: "How do I get product reviews -- and what do I do once I have them?" Of course, one answer to both those questions is: "email." And it's an answer that many of the top online retailers that I track have figured out already. Looking back over the past year, I've seen many examples of retailers using their email programs to spur product reviews, and then using their product reviews to spur email marketing conversions.

Here are six strategies for tapping the synergies between product reviews and email marketing:

1. If you launch product reviews on your site, tell your subscribers about it. This is a great way to build some steam behind your launch and start the hard work of getting that first review of a product. Your email subscribers are among your most engaged customers, so they are fertile ground for generating reviews. This year both Sam's Club and Office Depot have used their email programs to announce the introduction of product reviews on their sites, and last fall Avon did as well.

To be on the safe side, don't assume that customers know what product reviews are, that they are allowed to review products, or how to review a product. For instance, when Sam's Club announced the introduction of product reviews in a Feb. 2 email, the email linked to a landing page that described how to review a product in three easy steps and provided some reasons why you'd want to review a product. 

2. Ask subscribers to review products. Consumers generally write product reviews because they're asked, so don't be shy.

Consider using an incentive. While you can appeal to subscribers' vanity or need to be heard to get them to write reviews, dollar incentives will probably work better. That's especially true if your product review program is young or your customers aren't as engaged. Gift card sweepstakes are the incentive of choice among the top online retailers like Alibris, Bass Pro Shops, Blair, Office Depot, Orvis and Sears.

Consider using tiered incentives. All product reviews are not created equal. For instance, product reviews with customer-generated images are worth more than ones without. And video product reviews are worth more than ones with images. Rich media sells, so why not give customers a little something extra if they go the extra mile in their product reviews? That's what PetSmart did with their Shoot for the Stars Ratings & Reviews Giveaway, giving reviews an extra sweepstakes entry if they uploaded a photo review and an extra two entries if they uploaded a video review. That was definitely a Web 2.0 take on customer reviews.

That first review of a product is also arguably much more valuable, since they ease the way for additional reviews. So how about incentivizing customers to generate those? Northern Tool did that in an Aug. 18 email, offering reviewers an extra chance to win a product giveaway sweepstakes if they reviewed a product that hadn't been reviewed yet.

3. Use purchase-triggered emails to ask customers to review the product they bought. Depending on the kind of product purchased, wait two to four weeks after delivery and then send an email asking  customers to share their opinion about the product. Don't pester customers for reviews, so consider this a one-and-done tactic per purchase.

At eTail East earlier this month, Milton Pappas, executive vice president of corporate marketing and ecommerce for Redcats USA, which operates Chadwick's and other retail brands, said, "If you're looking for an incremental email that will generate a little revenue and be safe [in terms of generating few spam complaints], this is a good one."

4. Leverage your product reviews in your promotional emails. Once you have your product review program humming along, you can turn around and leverage all those reviews in your email messaging. Generally you can do this one of two ways: (1) You can highlight top-rated products or (2) you can use product reviewers' comments as testimonials.

For instance, Crutchfield has highlighted top-rated products in their emails, with an added twist in that they tell you in the email how many reviewers the rating is based on. That's a nice piece of transparency, so subscribers can see that that 5-star rating isn't based on one or two reviews. And Blair has highlighted top-rated products and cherry-picked reviews to use as testimonials in their messaging. Combining the ratings with quotes from reviews can definitely be a powerful one-two punch.

However, when using testimonials from customer reviews, you may want to test how your subscribers respond to the inclusion of reviewers' names, which lend credibility to the testimonial but can also be off-putting depending on how creative they got with their screen name. You may consider genericizing it to something like "online reviewer" or "online reviewer from New York" if you have location data.

Consider branding your rating system. Everybody understands star ratings, but consider using a rating system that's a bit more branded. For instance, Sam's Club uses diamonds that are the same shape as their logo, Petco uses paw prints, and Blair uses blue ribbons. Macy's uses stars, but it's the same red star as in the company's logo, so it's not quite so generic.

Consider using an appeal for product reviews as a submessage in these emails. When you're highlighting top-rated products, your subscribers may be receptive to an appeal or incentive to write reviews themselves. Bass Pro Shops, Blair and Orvis are among the retailers that have done this.

5. Highlight social network links. While the goal of most customer review programs is to get reviews on a Web site, that's not the way that all consumers want to review products anymore. Some customers, particularly younger ones, may be more interested in sharing their opinions via their preferred social networks. If you offer that capability, why not include that in your customer review email messaging? Urban Outfitters is the first retailer I've seen highlight social network links along with its product review appeals. Depending on your audience, getting social network links to your products may be more powerful than getting the on-site reviews.

6. Segment out product reviewers. A tip of the hat to Pappas of Radcats USA for this idea. At eTail he suggested that marketers segment out those customers that review products and treat them differently. He wasn't aware of any retailer doing that, but supposed that targeting these brand influencers could be powerful. At the Email Evolution Conference in February, Lawrence DiCapua, Pepsi's senior marketing manager, said that the company identifies email forwarders and treats them differently, rewarding them with a VIP program within the Pepsi Extras loyalty program, along with others who show acts of evangelism. So targeting product reviewers is just one more way to identify and segment out mavens in the hopes of using their influence to your benefit.

 I'm sure there are other synergies between product reviews and email marketing as well. If you know of other tactics or want to share your experiences with any of the tactics above, please comment below. Thanks.