By Savicom News

Subject Line Testing

A high email open rate (emails opened over emails sent) is the Holy Grail of any email marketing program. It not only shows you that your audience is interested in your messages, but it also shows ISPs that your messages are coming from a legitimate business and will continue placing your messages in the Inbox. As we previously discussed in our Engagement & Inboxing article, even an opened message followed by a click to unsubscribe is better than an unopened message that's deleted, or manually sent to the spam folder. Here are some tips you may consider to make your subject lines stand out.

Decide on the Purpose of the message

Before you begin writing down potential subject lines to test it's important to think about what exactly the purpose of the message is.

  • Is it a big sale?
  • Is it a standard newsletter deployment?
  • Is it an informational message?
  • Is it a triggered campaign?

What to Test

Once you've written down a few subject lines pick the ones that stand out best. Although your subject lines have the same purpose – to get users to click through to your message – different subject lines take different angles to achieve the same goal.

For example: you can tout a big sale in different ways with, "See what's in store for the biggest sale of the year." vs., "We have gadgets, gizmos, and more at our biggest sale of the year." The first subject line is vague as to what's on a sale and presents a bit of a mystery as to what's inside the message. The second is more specific and presents a potential for more items on sale inside. Although it's usually recommended to go with the more specific subject lines it's important to test general subject lines from time to time just to get a feel for where your audience is at.

Your Tools

Branding, mentioning your brand or slogan on your subject line, can prove to be an effective way to get people to open your messages, especially in a Welcome Email or Forward to a Friend Email series. This can be helpful if your business is just getting started or if you have more of a niche business. You'll want to make sure that the brand name or slogan serves as a supplement to the main purpose of the email message inside. If you find that your subject line is getting too long remember that you also have Pre-header Text as a tool to get more of your message across.

You can also test personalized subject lines that include a first name vs. some that don't, emojis vs no emojis, or a combination of both. Just remember that the goal is to get users to open your message. If your subject line and pre-header text seem too busy or lack focus, ask yourself, "would I trust this enough to open the message?"


When conducting subject line tests remember that the relative size of your test group vs the size of the deployment list is important to consider. We typically suggest a test group that's 10% of the total deployment list however, if you have a small sending list of only a couple of hundred email addresses you may want to choose a smaller sample that's still large enough to provide a statistical significance. You can adjust this as you see fit but consider that any address that is sent a losing subject line could have potentially responded better to the winning subject line.

Remember to test strong, focused subject lines that are different enough from each other that you can draw significant conclusions from their results. Make subject lines pop by personalizing them, adding emojis, and using pre-header text. You're not just subject line testing to get this one particular message a high open rate, you're also testing for future messages.

Savicom is a scalable email delivery engine and self-service ESP with proprietary delivery technology and a powerful interface to help you market smarter. Browse our Resources section to find other tips, tricks and insights to market smarter.