Subject Lines 101

Helpful Tools and Tricks for Business Development

David Berardi
3 min readDec 21, 2020

In a world of increasingly automated and sophisticated email communication, subject lines have become one of the most effective ways to make emails stand out. Studies show that of the 347 billion emails sent each day, 55% of them are “spam.” The volume of emails we send and receive makes it harder to know what’s important,, but a good subject line will cut through the noise and compel a recipient to make the conscious decision to open your email.

Check out some of these best practices and tricks for crafting the best subject lines for your sales organization.

Keep things brief

Subject lines between 1 and 4 words are the highest performing across the board. After around 6 words, open rates begin to drop. Some examples of high performing 1–4 subject line emails are the follow:

  • “Meeting”
  • “Question”
  • “<Sender Company Name>”
  • “Hi”

Your emails shouldn’t look like spam

If your subject lines look too similar to marketing promotions or spam, there’s a chance it’ll never even hit your prospect’s inbox.

One tip to avoiding being flagged as spam is to avoid using “Numbers” in your subject line. Subject lines that include numbers are 4x more likely to be marked as spam.

Another trick is to avoid spam filter keywords, such as:

  • “Double Your”
  • “Cost”
  • “Free”
  • “Discount”
  • “Save Money”
  • “Sale”
  • “Urgent”
  • “Congratulations”

Use names and ideas that people already know

Using a Co-Worker’s name in a subject line still remains the most effective way to get a prospect to open your email. Research shows that using a referral gives you a 500% higher open rate than traditional flat emails. here Here are a couple of the most effective ways to write subject lines use familiarity for results :

  • “Joe Smith / <Prospect Company Name>”
  • “Joe Smith Referral”
  • “Joe Smith / Call”

Another way to use names and ideas that people know is in a congratulatory but specific way. This strategy works for a couple of reasons. First, it shows that you are up to date with industry knowledge enough to know that the company had a major event. Additionally, if someone did just have a major event / acquisition / milestone and they get an email with the subject line referencing it, they may think it is directly related and important to the event, so there is a much higher chance they will open it. Last but not least — everyone loves to be congratulated for an achievement!

Iterate Constantly

Just because a subject line works, doesn’t mean it can’t be working better. In our ever changing world, it also doesn’t mean it will work forever. Pay attention to how your organization grows and adds new talking points.

Did your company just hit a major milestone for adoption?

Did your product just add an awesome new feature?

Try mentioning that in the subject line.

A great way to iterate constantly and keep messaging fresh is through A-B testing subject lines. A-B testing is simply sending the exact same email content to someone, but using two different subject lines. If done correctly, this will tell you which subject line has a higher open rate, which should theoretically lead to higher reply rates.

Put into Practice

Subject lines can be crucial to your company sales success, and are not to be overlooked! Many organizations fall into the trap of using the “Subject Lines” of the year, and next thing you know, your subject lines are the exact same as everyone else’s. Try to keep it brief, utilize referrals and specific, familiar ideas, and iterate constantly, because even the best subject lines wont work for ever.



David Berardi

David is the Business Development Team Lead at Rhino, a fast growing startup based out of NYC.