This is a guest post by Jesse Langley.

Email marketing isn’t cut and dried. You don’t just offer something in exchange for an email address and then never follow through. You also don’t over-deliver and essentially just start spamming your subscribers.

Seth Godin wrote an entire book on permission marketing, and it’s well worth a read. The basics, though, hinge on the fact that when your subscribers hit the button that submits their email address, it’s for a reason. They agreed to sign up for your updates and your promotions.

Unlike a retail store, you don’t have goods to hawk. Instead, you’re trying to sell people on a blog or an idea, or even a single book. However, that doesn’t mean you can violate the sacred social contract of email marketing.

State Your Purpose and Keep it on Task

One of the best ways to encourage subscribers is be upfront and tell them exactly what they’re getting into. If you’re sending random alerts, let them know how frequently you’ll be in their inbox. If you’re sending weekly emails highlighting the best posts of the week, call it a weekly newsletter.

Think of your email subscribers as your most valuable assets. Don’t mistreat them by spamming them or doing the unthinkable–selling your email list. Think of that list as a sacred bond of trust between you and your subscribers. Break it, and you’re asking them to take their business and time elsewhere because you don’t value them.

Be Purpose-Driven

Never send an email out if you can’t immediately state its specific purpose. Driving readers to your site isn’t a real purpose, either. It needs to apply from your readers’ point of view. Why should they open up this email? And if they do open it, what are they gaining from it?

Remember that you promised them value for their time. This is when you deliver. If you’re delivering news updates from your blog and you’ve been on vacation all week, don’t spam their inbox by sending them an email with little to no content in it.

Holiday emails can be cute and adorable, but they’re not something your readers are looking for from you. You’re not their Aunt Sally, you’re a generally faceless source of information and they’re an email address on a list for you. Don’t force congeniality on them, or they’ll hit the dreaded unsubscribe button.

Don’t Forget Your Purpose

Too often, site owners try to branch out, and they end up going too far. Take even Martha Stewart, for example. If you sign up for her email list, you’re not just getting great recipe tips. You’re also getting emails from all of her partners and information about holiday decorating, organizing and her television show. Your average reader isn’t going to want to know about all of that. They’re interested in whatever prompted them to originally give you their information. Step beyond that, and you’re going too far.

However, there are times when you’re legitimately going to want to offer more to subscribers. You know they enjoy your work and you feel like they’re pulling for you to grow. Be wary of embracing the warm fuzzy feeling that comes with subscribers, but you can still reach out occasionally and tell them what’s happening in your world.

If you’re launching a new site or a new category on your original, go ahead and send an introductory email letting them know that it’s there and it’s still you and you’re excited about it. Don’t send them frequent (or even two) emails about it if they don’t sign up for that separate service. Instead, let a byline with both site names at the bottom of your page do the work for you and keep your subscribers happy and contented.

However you’re reaching out to subscribers, keep your purpose clear throughout each of your exchanges. Any amount of duplicity, carelessness or regret can easily scare away those who could have been faithful subscribers.

Jesse Langley is a writer and editor living outside of Chicago. In addition to writing for various clients, he’s also an online learning advocate. Jesse is writing on behalf of Colorado Technical University.