Data-Backed Insights on Effective Cold Emails [Webinar Transcript]

Data-Backed Insights on Effective Cold Emails [Webinar Transcript]

As a part of the stellar lineup at the Cold Email Deep Dive virtual conference last month, we had Vlad, our VP of Growth (formerly SDR Lead) here at Reply chime in with the data-backed insights on effective cold emails

As the person who set up most of our cold outreach campaigns over the past few years, he shared some of the takeaways from our analysis of millions and millions of emails sent through Reply.

Watch the full presentation (+ more) on-demand

Here’s the transcript of the presentation for you to scan through. Enjoy!

Data-backed insights on effective cold emails

Here at Reply, we’re lucky enough to have the ability to get data-backed insights about cold emails because we can analyze the anonymized data of our customers – millions of emails sent through our platform each month. 

So we will be talking about data-backed insights on effective code emails: What works, what doesn’t, and how (I have seen this question in the chat a few times) can you get more replies?

Namely, my presentation today will consist of 3 parts:

  • Subject lines insights (length, letter case, marketing words, dos & don’ts)
  • Cold email templates insights (length – number of words and paragraphs, number of questions, marketing words)
  • Bonus content

Why it matters? 

Let’s kick things off with some thought-provoking email stats.

  1. 99% of email users check their inbox every day (source)
  2. 33% of email recipients open an email based on the subject line (source)
  3. 45% of subscribers say they are likely to read your email because of who it’s from (source)
  4. Mobile devices show up to 30 characters from an email’s subject line (source)
  5. Emails are the first thing 58% of people check in the morning (source)
  6. A majority of email views come from mobile devices (41%), followed by the desktop (39%) (source)
  7. The number of email users worldwide just keeps growing – we will have almost 4.6 billion email users in 2025 (source)

This last point shows that cold outreach won’t die – I hope so, right? We will have lots of new users in different countries and continents, they will adopt email clients, and probably they will run businesses, and they all will need an effective way to communicate. So email will still be an effective (I hope so and I think so) channel this decade.

Cold email subject lines insights

So let’s get started with subject lines. One thing I’ve always been curious to find out is: Could the length of the subject line influence the open rates? So we decided to grab this data and analyze the subject line length (number of words).

And we can say for sure that subject lines with one to four words generate the highest open rate (on average). Then it starts declining: The more words you have in your subject line, the longer the subject line is – the fewer opens you will get.

The same, by the way, happens with the average reply rate. For some reason, people dislike replying to emails with long subject lines. 

An interesting insight here is that there is a huge red flag for empty subject lines. Never send emails with empty subject lines because on average your open rate will be just 20% (compared to 32% on average based on our analyzed data). 

So yeah, I’ll recommend you stick to 3 maybe 4 words max, and then just play around with this data. 

On the other hand, I’ve seen similar research on subject line length (number of words) and they say the opposite – they say the more words you have the fewer replies you get, like significantly. So we will analyze this data set again just to make sure everything is correct here. But again, just play around with your subject line length and stick probably to the shorter ones.

As you can see, subject line length matters. Here’s an email I received a few days ago that has six words and the sixth one is almost invisible. So I understand, it’s my name but it doesn’t make sense, I don’t know what you want to say, so probably 4 to 5 words or 3 to 4 to 5 words is a perfect choice.

Next, let’s talk about the letter case.

As any other sales leader, sales person, I’m receiving dozens of cold emails per week. And recently, I’ve noticed a trend that some SDRs and salespeople use all lowercase words (as you can see in option #1 below). 

  1. all lower case words → sales development process at
  2. most lower case words → Sales development process at
  3. most upper case words → Sales Development process at

I got curious: Is this a shiny new trend or is this something that could help them get more replies and more opens? So we analyzed these three patterns and I can surely say that subject lines that contain all lowercase words typically generate fewer opens on average.

As we can see here most uppercase subject lines generate more opens than an average result. So my suggestion here is not to use all lowercase words. 

Again, if it works for you – that’s fine, that’s your choice. But typically I stick to the third variant– most upper-case words. 

And then this morning I saw an interesting post on LinkedIn where someone said: Hey whoever invented the idea that salespeople should ask a ‘quick question’ is a genius because this person can easily filter out all these generic cold outreach emails! And I have seen this as well, I have seen thousands of cold emails with this simple subject line ‘quick question’ so we have analyzed this too. 

As you can see here, this type of subject line typically generates fewer opens on average, and more importantly, it generates fewer replies (2.5% vs 3% on average). It’s the same with “just question,” and “quick chat.” By the way, “quick chat” works better, but again, on average reply rate is also lower here.

It’s interesting, that the subject line “referral” is cool, probably because it’s a warm email and it works.

Cold Email Subject Lines Cheat Sheet (+70 Top-Performing Templates)

Download the cheat sheet with the words guaranteed to boost your email subject line performance (and the ones to avoid) + 70 ready-to-use templates.

Data-backed insights on effective cold email templates

Let’s move on and talk about email templates. Again, length is super-important here – probably, the most important metric of your cold email template. Data says that in this case less is indeed more.

An email that contains fewer than 50-70 words (something between 50 to 70) generates the highest possible reply rate and ‘interested’ rate. So the longer email is the fewer opens and replies you get. 

So probably my suggestion here is to stick to something between 50 to 70 words max, and it makes perfect sense! There is a study saying that on average people spend between 11 and 14 seconds reading brand emails. It’s like 20% of a minute. 

Just imagine this: 11 seconds! Probably, brand email is something HTML edited, but again, I assume that cold outreach email is a kind of brand email because you’re a stranger, you want something from them, you reach out to them, so can be considered a brand email. 

So if we assume that people spend 11 seconds reading emails from strangers (brand emails) and then we use another chart that people typically read at a speed of 250 words per minute, it means that if we want to grab their attention for 11 seconds our cold emails should be 50 words max (or something between 70 to 100 words if they read faster).

And, as you can see on the previous chart, it indeed makes sense. So probably, I would say this is the most important metric – length – and I would suggest you stick to 50-70 words in your templates.

Now let’s talk about the length in terms of the number of paragraphs. Once again, probably people don’t like really long cold emails and the same applies to the number of paragraphs. Here’s an example of my cold email with four paragraphs.

We analyzed the average reply rates and ‘interested’ rate of cold emails based on their paragraph length, as you can see here, the cold email templates that contain only two to three paragraphs generate the highest possible reply rate and “interested” rate.

Then it sounds like it doesn’t matter if your email contains 6, 7, or even 10 paragraphs, if you grab the attention in the first sentence, probably, they will read everything else. But if you want to maximize your results, I would suggest sticking to 2, 3, or 4 paragraphs, just like the email example above. Maybe I can even improve it and use just 3 paragraphs, but again, I have no opinion on this for now.

One of the other elements of a cold email template I decided to analyze is questions. I was curious because sometimes I see cold emails that contain more than one question. So typically it means “Okay so you want from me something let’s say #1 then you won’t something #2 then I’m a little bit confused, because I don’t understand what you want from me”. 

Remember, the main goal of cold outreach is to have a super-targeted, super-straightforward CTA, like, do you want them to sign up for something, book a demo, simply reply, or click a link? So don’t use a lot of questions.

As you can see here, it’s interesting that the average reply rate for cold emails that contain zero questions is the highest. I have heard a lot of things about soft CTAs, so probably soft CTA with no questions will help you get surprisingly more replies. And the average “interested” rate is also higher here.

So the more questions you ask (you can see, we can assume that) the fewer replies you will get. And if we compare cold email templates with three questions, we will see that they generate 30% fewer replies on average.

So what’s my recommendation here? I would say use soft CTAs like “Worth a conversation?” or my favorite one with zero questions is “If this is something you’re interested in happy to share more details” or something with this zero questions but a soft CTA.

And the last batch of things we decided to analyze for this event is the email content – whether or not pictures, links, and GIFs influence your results.

As you can see here, indeed three of them will decrease your average reply rate. And it totally makes sense because sometimes links could contain a long tail URL and are not good for email inbox placement, for email providers. So probably that’s the reason. 

For GIFs, it’s a completely different story, because typically they weigh a lot maybe 100 kilobytes or maybe sometimes even megabytes, so again email providers dislike heavy cold emails with GIFs. it’s the same with pictures. So my recommendation here for the very first cold email in your sequence is just to send blank text emails with no pictures, with no GIFs. Let email providers think that it’s not spam. When they get used to your domain, to your email address you can send maybe pictures or links in your second, third, or fourth email follow-up.

It’s the same with links, but it’s not a big difference compared to an average result, so probably links are fine.

How to write better cold emails, according to data

Data-backed insights on several aspects of effective cold email copy, including length, variables, questions, and non-text elements.

If we summarize everything we’ve discussed today, here is a cheat sheet for you on how to easily improve your reply rate and deliverability.

Again, 33% of people open emails based on subject lines, so I will recommend you

  • use 1-5 words in your subject line
  • never send empty subject lines
  • use any letter case (but not all lowercase)
  • think of a subject line as a short version of an email 
  • no “quick question” (don’t use this subject line)
  • always A/B test your subject lines

And when it comes to cold emails and cold email templates people typically spend 11 to 15 seconds reading brand emails (I’m not sure if it’s true for sales cold emails but I assume yes) so length is super important. So I would recommend you stick to 50 or 70 words or maybe even fewer. I think about this as a “tweetable email” – something between 200-300 symbols. Paragraphs are also important, so stick to 3-4 maybe 5 paragraphs max.

Use one question max and use soft CTAs, like “Worth a conversation,” “Is it something you’re interested in,” or “How do you think is this relevant to you,” “Do you think it’s interesting? If so let’s have a conversation,” etc.

Also, content matters, so avoid links, GIFs, and pictures in the very first cold email and use them in your follow-ups. And again, always A/B test.

Here’s an example of my sequence. Typically, I try different subject lines and sometimes I change just CTAs, maybe my wording, just some small tweaks, and send maybe from 500 to 1,000 emails for each variant and then grab the best performing one. 

Yes, it requires some passion, and it requires some time, but again, probably ChatGPT will help generate ideas for you faster and this will help you A/B test. Because everything I said today it’s just data-backed, it’s an average, maybe you have better results already, I don’t know, but it’s the perfect time to experiment.


Watch the full presentation (+ more) on-demand

Check out more hands-on masterclasses from Vlad:

And make sure to register for the upcoming Sales Development Excellence 2023 – a virtual event packed with expert panel discussions, masterclasses, and hands-on workshops covering the key aspects of sales development mastery.

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