First impressions are everything.

And in the world of cold email, first impressions matter. Those first impressions often take form in the subject line you choose to use for your email outreach.

So what should you do to get the most out of your subject lines (i.e. increased opens)?

Keep it short + to the point

First, you’ll want to keep your subject line short and to the point. After analyzing 12-million different emails sent through the Interseller platform, we found that subject lines with 20 or fewer characters tend to perform better.

subject lines

If your subject line is too long, it will get cut off (especially on mobile devices). Think about that real estate and how you can condense it to be as impactful as possible in a limited space.

Gmail will use ellipsis to manage spacing on one line. And, if you’re using an action item, keep it to the front of your subject line (think webinar promotion push or other marketing plays here).

Test subject lines to find what works

With any cold email strategy, you’ll always want to put things into play and test them for yourself. Just because one subject line performs well for one person and company, doesn’t mean it will automatically translate to what you’re trying to do.

Your open rate will be a good indicator of subject line success, so you’ll want to aim for a 50% or higher baseline for opens.

For the first half of 2021, here are the top 4 data-backed subject lines I’ve personally used and found success with opens and replies.

[First Name], about your LinkedIn post (or comment)

  • 73% open rate on first email with this subject line

  • 6% reply rate on first email with this subject line

  • Using reply in thread for 2nd and 3rd email in sequence = additional 7% reply rate

[Your Company] + [Their Company] 🚀

  • 55% open rate on first email with this subject line

  • 3% reply rate on first email with this subject line

  • Using reply in thread for 2nd, 3rd + 4th email in sequence = additional 10% reply rate

The one word subject line (i.e. growth)

  • 63% open rate on first email with this subject line

  • 2% reply rate on first email with this subject line

  • Using reply in thread for subsequent emails = additional 11% reply rate

congrats [First Name] 🥳

  • 88% open rate on first email with this subject line

  • 13% reply rate on first email with this subject line

  • Using reply in thread for subsequent emails = additional 14% reply rate

Feel free to take any of these subject lines and apply them to your own cold email outreach. But, just keep in mind that having a solid subject line is just the first step in a successful strategy. Once you get your opens up, you’ll still want to focus on how to win them over with the body of your email.