This might seem counter-productive since you 

Try using A/B testing for your email marketing campaign. This basically entails creating two very different versions of the same email (A and B) and sending "A" to half of a small test group and "B" to the other half. Whichever half receives the most positive response is the one that you should be using for your campaign.One way to keep your email readers engaged is to ask them questions. These should not be rhetorical questions, either. Provide a feedback channel they can use to send you answers. You could ask for direct replies via email, or send your readers to your social networking pages. However you arrange it, asking for two-way communication is a great way to cultivate loyalty in your subscribers.The emails you send out as part of your marketing campaign should start out with a welcoming, personalized tone. Include the name of the recipient in the subject line and the opening of the message. This will make your customers feel more receptive to your message and be more likely to patronize your business.Successful email marketing campaign lists are built organically. Forgo renting or buying pre-made lists, and instead start one from scratch. Get business cards at industry events and have opt-in links on all your web pages. Offer incentives to your subscribers to forward your material to associates they know would be interested. Your niche already has an existing network of social ties within its community, follow those paths.Use plain text. Plain text emails will be received as more personable and HTML can be more difficult for some people to read. Some email readers may even prevent the delivery of HTML, depending on user settings. Plain, simple text will always be easy to read and very well received.Keep your email content fresh. Don't start repeating old information or re-using anything that you have previously written about in your emails. Your readers know when you've already said something and when you're out of ideas. Furthermore, if you notice that something in your emails, like templates, images, etc. just aren't garnering attention anymore, don't fear changing things around.One tip to enhance your e-mail marketing campaign is to send out regular updates to your customer base, even if not much is happening in your business. These regular updates can be short and sweet. They remind your customers that you are staying busy and want to keep in contact with them.Be sure to include an easily-completed unsubscribe link in all of your marketing emails. Customers who are unhappy with your emails or who no longer wish to receive them can do more damage to your reputation than you might think. Reducing the size of your email list through unsubscribing is better than angering customers who no longer want your mailings.