Among the many moving parts of a successful marketing plan, emailnewsletters are still a vital component. It remains the most direct, one-on-one place to engage customers. And email marketing's integration with social media means greater opportunities -- and challenges -- when it comes to creating content that can ignite conversation and inspire sharing on social platforms like Twitter, Facebook and LinkedIn.

Last month, I discussed how social media websites have profoundly changed how consumers expect to interact with brands. Business owners can no longer compete by talking  at customers and prospects. Instead, people now want businesses to talk  with them. They want to know their viewpoints are not only heard, but also make a difference in how a business operates. They want to be a part of your story.

While planning out your e-newsletters for the remainder of the year, consider these four ways to make your content more sharable on social media.

1.Engage customers in content creation. You may think you know what's most important to your customers, but you can glean a lot more about their needs if you ask them. Use surveys, polls, and crowdsourcing (asking questions on Facebook, Twitter, LinkedIn, and blogs) to find out what's affecting your customers' lives. Invite them to share their experiences related to your business and industry. You can feature the most compelling stories in your newsletter and across social channels. The individuals you feature are likely to share that content over their own social networks. Of course, remember to ask permission before sharing customer stories in any public forum.

2. Vary your newsletter content. Readers are most engaged by content that's relevant to their lives. Help them see themselves being helped by your business in the stories you create. Formats that work for newsletters and social sharing include: