How to Write Cold Email Subject Lines That Get Opened (2024)

One of the most crucial factors that dictate the success — or failure — of your cold emails is not their content.

It’s that short but impactful subject line.

At first glance, they may seem like short phrases you have to compose just so you can start sending out your emails.

In reality, they bear a lot of weight and influence the way your emails are delivered to inboxes.

The way you craft your title, word what you want to say, and even stylize it with emojis can significantly impact the performance and effectiveness of this outbound marketing strategy.

If you want to make sure that your cold emails work and avoid going straight to spam, here are two effective tips:

1. Avoid or Reduce the Use of Spam Trigger Words

The best and most straightforward way to avoid going straight to the junk box is to avoid or lessen the use of certain trigger words.

Using these every once in a while does not automatically hurt your delivery rate, but it’s still best to find good synonyms as much as possible.

To give you an idea of the most notorious spam filter triggers, here are 15 of them:

  • Amazing stuff
  • Affordable
  • Cash bonus
  • Earn extra cash
  • Free
  • Fast cash
  • Guarantee
  • Increase sales
  • Limited time offer
  • Opportunity
  • Promise you
  • Save $
  • Serious cash
  • Web traffic
  • Weight loss

Here are 10 more terms that are not as notorious as those above, but may also land your email in the spam if used frequently:

  • Act now! Don’t hesitate!
  • Additional income
  • Click below/Click to remove
  • Easy terms
  • For instant access
  • Free consultation
  • Great offer
  • No gimmick/No fees/No obligation
  • Satisfaction guaranteed
  • Special promotion

Spam filters assign ratings to your emails according to how you used the terms mentioned above.

Using the word “free” or “limited time offer” once in a while will not necessarily harm your email especially if you have a good delivery record.

However, it’s a smart idea to use them as sparingly as possible.

2. Format Your Headlines Properly

Aside from ensuring that your headline satisfies spam filters, you must not forget about human spam filters — make sure that it does not put off your recipients!

One of the fundamentals of formatting headlines properly is to always double-check for spelling mistakes and observe proper punctuation.

A seemingly simple misspelling can make recipients doubt your professionalism.

Moreover, you should avoid writing subject lines in all caps and putting false promises.

If they don’t find in the body what you guaranteed to give them in the subject line, they most likely won’t pay attention to your next emails anymore.

Including emojis in the subject line is also worth exploring.

An Experian report shows that 56% of brands that include these in their subject lines have higher open rates.

However, you must be careful when using them.

Unlike letters and numbers, some emojis aren’t standardized. They can be displayed differently depending on the recipient’s device.

If the emoji you used in your subject does not have support or does not exist on other keyboards yet, your recipient will only receive an ◻︎ in its place.

Bonus: The Best Cold Email Subject Line

There is one subject line that has performed better than any other for us over the years.

It’s also the simplest subject line you can imagine.

It’s: “Quick question”

For whatever reason, people almost always open (60%+) an email with this subject line.

You can also make variations like “Quick question for {name}” and personalize it further.

Give it a try!

Bonus: Don’t Forget About Cold Email Deliverability

If you’re using proven subject lines and still getting horrible open rates, you might want to make sure you have taken every step to make sure your cold email deliverability is the best it can be.

You want to be hitting the Inbox (or at worst the Promotions tab) as much as possible.

Pro tip: Get in-depth tutorials on hitting the inbox and much more in the Lead Generation Masterclass


What you put in your subject line and how you format it significantly affects the performance of your whole email.

Considering this, it’s a smart idea to spend enough time crafting insightful, enticing, yet well-balanced subject lines.

Do not just wing it and go with whatever comes into your mind at the last minute.

Follow the tips above and you’ll be well on your way to crafting cold emails that work and actually get read.

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