You split your email subscriber list into “cold” vs. “warm” leads so you can compare similar groups of customers in this test. You prepare two versions of your email—one with the normal subject line, and one with a much shorter, punchier subject line. You send half of your cold leads the normal subject line and half of your cold leads get the new, exciting subject line. You also send half of your warm leads the normal subject line, and the other half get the new subject line.
Whenever possible, add a personal element to your emails. Most email tools allow you to enter shortcodes that will be replaced with the recipient’s name when the email is sent out. Emails from Treehouse Co-Founder Ryan are always fun and personal. The subject lines are creative, messages are sent "from" Ryan's email address, and the content is personalized. If you reply to the mail, you'll even get a prompt response from Ryan himself!
Edit. Even editors need editors. When you're working on your publishing calendar, leave plenty of time for the editing and revision process. Once you send a campaign, it goes straight to the inbox, and you can't go back and update it. Newsletters contain meaningful content, and sloppy ones reflect poorly on the companies who send them. Grammar and style are just as important for email as they are for websites and blogs.