Customers receive more promotional emails than ever before. To stand out from the crowd and to avoid the “Deleted Items” folder, emails must contain a compelling subject line. Follow these three tips to create subject lines that will make your email messages irresistible.

1) Cultivate consistency

If customers have opted into your email distribution list, then they will see many subject lines from your company flow through their inboxes. To keep customers from clicking “unsubscribe,” you should make sure that your subjects have a consistent personality and structure. Also, make sure that your subject lines are always relevant to the content of the email. Don’t promise a special promotion and then fail to deliver that promotion in the body of your message. Consistency creates trust, and trust will generate clicks.

2) Create a sense of urgency

To advertise a limited time offer or promotion to your customers, put the deadline for the offer right in the subject line. You want your customers to open the email right away–after all, do you ever read emails that you’ve filed away for later? At the same time, if you don’t have a promotion with a deadline to offer your customers, then don’t create a fake promotion in your subject line just to earn that click. This ties back into the sense of trust that you want to cultivate with your customers.

3) Test, test and test again

Try sending your newly composed promotional emails to yourself and evaluate how your subject line looks in your inbox. In a sense, make yourself your own focus group. Are you creating copy that would make you want to open that email? Have you avoided capital letters and exclamation points so that your email doesn’t earn a trip to the “Junk” folder?

In addition to testing your emails on yourself, run test messages to small groups of people on your distribution list. Try some A/B testing in which you offer two versions of a subject line to your focus group. The subject line that earns the most clicks should be the one that you send out to the larger group. Plus, as you learn what your customers actually open and what they don’t, you’ll begin to create your own winning formula for delivering consistently enticing subject lines.