Mobile now influences 19 percent of all retail sales. This creates both a huge risk and once-in-a-lifetime opportunity if marketers can get their mobile strategy right. As we head toward 2015, we’re seeing more brands than ever adopt a “mobile-first” strategy. Marketers who want to share screen time with their customers had better make sure their content contains actual substance, or they will verge upon a difficult and dangerous gray area between a great message and “spammy” one.

Get a handle on spam. For mobile marketers, there are three types of spam to avoid.

First, because this is actually illegal, you will run into trouble delivering messages to customers who didn’t knowingly agree to receive your marketing email. You can provoke rampant frustration by exceeding the number of messages you promised to deliver. This might be be forgivable if the content is relevant, but you can get into serious trouble with the Mobile Marketing Association for doing this.

The most difficult spam to avoid is the most prevalent type -- anything your mobile customers they aren’t excited to get. This might be anything from delivering a message with irrelevant content to one that arrives at an awkward time.

Related: Creating Spam-Free E-Mail 

This type of spam will not cause legal problems but it definitely could create customer problems that damage your brand. Your customers recognize this spam when they see it. They will react by eventually opting out or, worse, sharing their negative experience with others.

Here are three pillars of mobile messaging you can use to ensure your message is relevant:

1. Time. Mobile is the only marketing medium where you get to choose exactly when your audience notices and engages with your content, with prime real estate space like the lock screen. This control means you can now insert yourself into the purchase process with a level of precision unheard of in the past.

2. Location. Your content also needs to take location into account. Think about where your audience is when they receive your message. Teenagers are likely to be in a different place than professional wedding planners. Your content should differ if your audience will be at home or at work.

3. Participation. Make sure your message resonates with your audience and they can do something to engage with it. Every message you send should be memorable to your mobile audience.

Related: How Not to Be a Spammer When Marketing Your Business

Remember, your audience is made up of actual people. Think of the last time you texted a friend You probably thought about what they were doing and where they were before you sent the message. Do the same for your audience. Try talking to them like they’re your friends. By keeping in mind that your audience are people, not statistics, you will avoid content that seems spammy to them.

Personalization is possible at scale. Rather than thinking of an individual person, think of the characteristics of the audience you’re trying to reach. If you’re texting young moms, make sure you speak to them like you would speak to young moms.

As a consumer, I view my favorite brands as more than just companies. They’re almost friends. My relationship with them goes way beyond the utility they provide. I can sense their company culture with every interaction. My Jeep is a means of transportation but the fact that other Jeep owners wave to me on the road takes my relationship with the brand to another level.

We all know spam when we see it. You can avoid being “that brand” by making your messages relevant and useful. If you do this, you can stand out from the madding crowd. Your audience will listen to you when you become like a friend.

Related: Five Tips for Better Text-Message Marketing