But with 680+ daily deal providers now peddling everything from discounts on high fashion to high adventure travel packages, the market is reaching a tipping point. As consumers inboxes fill up with multiple offers for mani/pedis, restaurants they’ve never heard of and discounts on ballroom dancing lessons, “deal fatigue” sets in, and messages that were once eagerly anticipated begin to look like something else entirely. (Hint: rhymes with ham.) The daily deal marketers that succeed and thrive in this hyper-competitive environment will be the ones who make smart choices about who they target, what they offer, and how effectively they leverage email as a communication medium.

When my company conducted a recent study on daily deals marketing, we learned a lot about what’s working for successful industry frontrunners like Zulily, Living Social and others, what’s not and how deal providers can do better. Here are some “detail-oriented” tips for standing out in the inbox, culled from our look at a cross-section of players who are leading the pack:

Relevance is king. The key factor that makes consumers shift their perception of marketing emails from “spam” to “message I look forward to opening”? Relevance. Even a 95 percent discount on carpet cleaning is meaningless to a person who has hardwood floors, after all. The deal ventures that don’t have a complaining subscriber base are those with highly sophisticated targeting — based on age, geography and special interest. For example, zulily, an online daily deals site selling gear and apparel for moms, babies and kids, has focused its product offerings around key verticals that correspond with the changing phases of parenthood. Since zulily provides a well-rounded selection of products for expectant mothers and children from infanthood to tweens, zulily members know that zulily emails are packed with the right deals for busy parents. Witty and conversational email subject lines engage parents and earn their trust, making zulily emails a “must open” every morning. Delivering deals that resonate with parents keeps zulily relevant in member inboxes each day.

Communication is a two-way street. Instead of talking “at” consumers, smart email marketing should establish a dialogue with its target audience. This means giving deal subscribers numerous opportunities to provide feedback about their likes, dislikes, needs and interests. For example, one thing that Groupon does really well is its welcome message. In it, the company immediately prompts new subscribers to provide preference information on the deals they’d like to see most, and to let Groupon know what companies they’d like to see deals from. Empowering consumers with a voice is a win-win. They feel more invested and engaged, and deal providers can learn a bunch of useful information that will help them tailor highly relevant (there’s that word again!) offers. Plus, self-reported data is more powerful than behavioral analytics (although information related to click-throughs and historical purchases certainly has its place.) Rather than inferring that a purchase of gourmet cupcakes means that a consumer wants to receive offers from every bakery in town, give your subscriber the opportunity to say so! (Could be that it was a once-a-year birthday gift kind of thing.)

It’s all in the timing. Nobody wants to have bad timing. Successful flash sale vendor HauteLook leverages burst email delivery to ensure that every message to its millions of subscribers arrives within the same 10 minute window every day. This enables them to emulate the experience of an offline sample sale, where women line up at the crack of dawn to get the best pick of the inventory. To make an offer feel less like junk that’s clogging up a person’s inbox, consistent timing can create a sense of expectation and urgency among subscribers that dramatically increases open rates, clicks and ultimately revenue.

Tailor the message to the medium. People don’t read email, they scan it, especially when it comes to marketing offers. You have about 3 to 7 seconds to convey your message before the recipient checks out, so keeping things catchy and to the point is critical. One flash sale company we looked at was using the subject line of its offers to list every brand name label included in the offer. This looked so cluttered and overwhelming! Email subject lines are like billboard headlines on the freeway. You need to deliver a clear, concise message at-a-glance. In the main message text, consider how spacing, bullets and headlines draw attention to the most compelling aspects of your offer. Prominent display of the price and discount percentage brings the value of the deal front and center, for instance. And resist the urge to use large chunks of copy as this can deter consumers from engaging further.

Distinguish yourself. In a space that is increasingly cluttered, being able to tout a unique value proposition is a big plus. Flash sale company Rue La La puts its “Rue 30” shipping guarantee front and center in email messages. Since there are not many other players that offer a one-time shipping charge that’s good for 30 days (hence enticing consumers to jump on more deals within their 30-day window) this gives the dealmaker a way to distinguish itself.

In an increasingly crowded market, daily deal providers can’t miss a beat if they want to stand out from the pack. When it comes to email marketing in such an environment, every detail counts, from the timing of your offer, to the words filling your subject line. Unless you can spark the consumer’s interest and get them to engage, it doesn’t matter how great the deal.