A strong opt-in email list is one of your hospital’s most valuable important digital marketing assets. As more and more people block banner ads on their computers and mobile devices, there’s tremendous value in patients and prospective patients giving you permission to send them emails.

What’s more, with Facebook and Google allowing you to target promoted content and pay per click ads at users with their email addresses, the inbox is no longer the only place to reach people in your email list.

Well-executed email marketing has an ROI of as much as 4,300 percent, but it’s hard to have much success if your list is lacking. Here are 5 ways to build a list of people who will actually look forward to your emails.

1. Share shareable content

The forward button was the original retweet button. It gets a bad rap because of all those chain letters everyone used to send (okay, some people still send them), but people still share content they love with their friends and family members.

Shareable content means content that’s actually useful to your recipients or to their loved ones. It means content that’s not the same as what everyone else is sending. It means content that connects with them emotionally and makes them feel like it’s meant for them, not someone else. Send content because you think readers will care about it, not because you have to check off an item on your to-do list. Combine all of that in an email and your subscribers will spread the word for you.

2. Make it easy to subscribe

Don’t make people hunt for your sign-up call-to-action. Whether it’s on your website or your blog, make sure the call-to-action is prominently displayed and designed to catch the eye. Run A/B tests to see what works best.

Don’t forget to include a subscribe link in your emails—that way people who get forwarded copies can sign up easily, too.

3. Show people what they’re getting

Most of the time, you have to do a bit of selling to get people to hand over their email addresses. After all, most of them are looking to get fewer emails, not more. That’s why you have to clearly show people what they’ll get in return.

Instead of just writing “Sign up for our e-newsletter,” describe what’s in each issue. Ask people to sign up to get healthy recipes or fitness tips right in their inboxes. If you’re sharing blog posts, let them know that they can receive all your best content without remembering to visit your blog all the time. If you’re sharing additional content, let them know what they’ll get that won’t be seen on the blog.

4. Give them something more

People love free stuff. Offering something as a prize is a great way to incentivize email subscriptions, but make sure you know what your target subscribers want. A Starbucks gift card might be almost universally desired, but some prizes have more specific audiences. Try to match it up with the theme of your content, like something for the kids or a night out if you’re sending emails to parents or a Fitbit if you’re sending fitness tips. Give them an extra chance to win if they refer other people they think would enjoy your emails.

5. Promote it everywhere

You probably already promote your email newsletter on social media, but why stop there? Put up signs in offices and waiting rooms. Add a subscription option to event registration forms. Make sure the sign-up URL on any print materials is short and memorable, so people can sign up on their smartphones or when they get home. If you’ve got the budget, purchase pay-per-click ads for keywords related to the content in your emails and take users to a landing page dedicated to subscribing.