At GrowthOK, we mainly focus on finding highly qualified and targeted leads for our customers, but we also live and breath cold email. We help a selective amount of customers with their outreach campaigns and we also send out hundreds of cold emails everyday for our own email outreach campaigns.

The most important thing when it comes to sending cold emails is following up with a prospect/lead that hasn’t responded to the initial email.

Because of this, we tested hundreds of different subject lines to see which one gets the best results. We also changed up some strategies over time to increase the response rate.

In this article, I’ll be covering all the best practices for follow up subject lines and the best subject lines with actual examples from our campaigns.


Best practices for follow up subject lines

Why are subject lines important? Because it’s the first thing anyone looks at when checking their email. Imagine all the times that you skipped opening the email due to an uninteresting subject line?

Following up with a prospect is super important, but you can send a million follow up emails and it won’t mean anything at all if they don’t open or respond to it.

There are a lot of things you can do to improve your open and response rate for follow up subject lines, but here are the ones that worked best for us.

Including a recent discovery about the prospect increases response rate

One of the most effective subject line and the one that worked best for us is by mentioning a recent discovery about the prospect.

You can simply check the prospect’s Linkedin or their Twitter to look for any updates or announcements. For example, the prospect could’ve just been mentioned on Techcrunch or maybe they just got a new position at another company.

This is where you want to mention that within the follow up subject line.

Here’s an example of a subject line for that situation:

“Hey {!Name} – Congrats on the new job at {!Company}”

Always include the prospect’s name in the subject line

Typically, you’ll want to use the person’s name in your follow up email subject line. If you don’t have it, you can use the company name instead.

Your initial email’s subject line should always include the prospect’s name if possible as well. Just make sure that you have a good source for your lead data that actually includes the first name.

If you need help with that, feel free to reach out to us at GrowthOK

The more you personalize your subject line, the more benefits you can reap. Good contact data is key.


The more data points the better..

Alright alright, now you might be thinking, “this is too much for just a subject line”. Remember, as mentioned above, subject lines are extremely important. The more personalized the better. This is why the more data points the better.

We saw a 32% increase in response rate when we included more than one data point in the subject line.

So, we tested two different subject lines. The first one was:

“Hey {!Name} – GrowthOK partnership inquiry

The second one was:

“Hey {!Name} – GrowthOK and {!Company} partnership inquiry.

And you might have already guessed it, but the second subject line receives a 32% higher response rate than the first one.

This is because we included a second data point in the subject line. Now, you shouldn’t spam your subject with data points, but two data points is usually the sweet spot for us.


Sounding like an actual human makes a difference

When it comes to cold emailing, you want to sound like a human. I mean at the end of the day, you want to talk to a human and not a bot right?

This is why mentioning the prospect’s first name in a follow-up email subject line is important. It creates a personal touch.

There’s a huge difference between a marketing email subject line vs a prospecting email subject line.

Which one of these do you think you would open?

“GrowthOK – Your number 1 source for quality leads”


“Hey {!Name} – Wanted to see if GrowthOK might work for you”

I think most people would open and read the second one because it doesn’t sound like a damn advertisement.


Examples of subject lines that work

Surprisingly in the B2B space, we tested a bunch of subject lines and follow up email subject lines that get high open rates are the ones which include the sender’s full name and their company’s name, plus the word “Introduction”.

Here’s an example: “{!NAME} and {!Company} – Introduction”.

You could also add your own company’s name to it as well if you like.

Now that works great for the initial email. Doesn’t mean that you can’t use it for follow up emails, but we noticed a slightly better version for a follow up email.

That is “Hey {!Name} – trying to reconnect…”

That tends to work better as a follow up subject line.


Complements work really well

If there’s something you admire about the recipient or their product and business, this can work well.

Here’s an example: “Hey {Name}, I love that speech you made on Techcrunch”. 

This is an example of a high level personalization. This is why you must do research on the lead before reaching out to them. Again, this doesn’t take hours, just a few minutes with a quick Google or Twitter lookup.

Get creative with this one. It could even be a past interview that they’ve done. It gives you a reason to follow up.


Mutual connection mention works

Another follow up subject line that works really well are the ones where you mention a mutual connection’s name.

Again, you should make sure it is legit and that you actually know the person or everything will go downhill.

An example of a follow up subject line for this would be:

“Hey {Name} – Saw that your friends with {Friend’s name}

That tends to work really well.



Of course, not the same follow up subject line will work for every company. You should personalize it depending on your goals, target, and industry, but this is what we learned after sending over 50,000 follow up emails for our own company as well as our customers.

Be the one salesperson who follows up enough to make the close, and you’ll be way ahead of the game.

If you have any follow up subject lines that tends to work well for you, please leave it in the comments below!

If you’re looking for highly qualified and targeted sales leads that actually convert, don’t hesitate to reach out to us at GrowthOK 

Author: Wilson

Wilson is a 3x entrepreneur and founder of GrowthOK. He loves and breathe entrepreneurship, growth, sales, and has a strong passion for crypto and blockchain related topics. You can follow him on Twitter @itswilson8

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