A scientific approach to outbound sales.

We believe that customer acquisition is an art, and we approach it with a lot of passion and creativity. However, we also believe that in order to do it well, we have to take it very seriously. And this means questioning and evaluating everything we do.

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Report 01

How many emails should 
I send to one prospect?


We believe that customer acquisition is an art, and we approach it with a lot of passion and creativity. However, we also believe that in order to do it well, we have to take it very seriously. And this means questioning and evaluating everything we do.
At Growbots we take a scientific approach to outbound sales, and we really hope that this report will encourage you to do so as well.
While doing outbound sales, or sales – a lot of us wonder, how many emails should I send to one prospect? How many is too many, and how many is not enough?
This report addresses this question. And if you are hoping we will give you an actual “right” number of emails you need to send to get the outbound sales results you are looking for – hang on, we will get there.

What data did we consider?

This report is based on data gathered from January 1, 2018, to August 15, 2018.
We analyzed 3.7 million emails sent by 401 customers via Growbots. The data is not limited to any specific sector, as we have customer across a broad range of industries.

Outbound sales terminology explained

An initial message – the first message you send to your prospect
A follow-up message – every subsequent message you send to your prospect after sending your initial message
An email sequence – a series of emails sent based on pre-set criteria
A warm response – a response which opens up a conversation, for example, “I want a demo”, a question, an objection, “I will forward your message to” etc. We identify it through our NLP (Natural Language Processing) algorithms.
A negative response – a response such as “remove me from your mailing list”, “not interested”, unsubscribes via an unsubscribe link etc.


How follow-ups impact your warm response rate

There is a general belief that sending more email follow-ups will have a positive impact on the overall effectiveness of an outbound campaign. To evaluate this statement we checked the warm response rate of each email follow-up sent in a sequence.
While sending additional email follow-ups brings in more warm leads overall, there are diminishing returns. Meaning — each subsequent follow-up results in fewer positive responses than the previous one.

For example, while the first follow-up has a warm response rate of 1.28%, the warm response rate of the fifth follow-up drops to 0.62%. This trend is clearly demonstrated in the graph below.



Since the warm response rate decreases with every next follow-up sent, how do you decide when to stop? And should you actually stop if every message brings in new leads, and as a result enhances the effectiveness of your campaign?


How follow-ups impact your negative response rate


To resolve this dilemma we evaluated another metric – the negative response rate. After all, we want to ensure we do not burn too many bridges.


A negative response includes all prospects who say they are not interested in your product or do not want to receive any further communication from you (unsubscribe/opt-out). These prospects leave your sales funnel.


Look at the graph below to see the results.



We have observed that the negative response rate drops but less drastically than the positive response rate, which is why we have decided to compare these two metrics.


The negative to positive ratio


We have decided to compare the negative and the positive response rate to check how many negative responses we had to receive to generate one positive response at every stage of a sequence.



The above graph clearly shows that in relation to the positive responses the number of negative responses increases steadily with every subsequent follow-up.

What does it actually mean? Even though every new follow-up you send generates additional warm replies, an increase in the negative to positive ratio means you will have fewer prospects in your sales funnel to contact in the future.
Let’s take the sixth follow-up as an example. Is it worth risking getting eight unsubscribers just to receive one positive response?

“Sending too many follow-ups can seriously damage your sender reputation.”

Bear in mind that your negative response rate does not include spam reports, so in reality, this number can be even higher. Sending too many follow-ups can seriously damage your sender reputation. It’s not worth the risk.

Worth keeping in mind

Outbound sales is all about timing. Just because a prospect did not respond to your email does not mean they are not interested in your product, or that they will not need it in the future. There might be dozens of reasons why they did not get back to you:

  • They might be under a contract with your competitor
  • They might have no budget for any additional products/services
  • They might be overloaded with work
  • They might be even going through some personal issues…

…and, most importantly, they might not be ready to resolve their problem just yet. Remember that your prospects need to be aware of the problem, be willing to fix it, and have the means to do so – these factors may not have lined up over the time period that you sent out your email sequence.
What you have to keep in mind is that things change. And we do not recommend beating a dead horse with a stick. Instead of sending tons of follow-ups, try waiting a couple of weeks and reaching out again once the situation has changed.

Recommendations and key takeaways

The number of follow-ups you send impacts your warm response rate. Obviously, the more follow-ups you send, the higher the total number of warm responses you will get.
However, each subsequent follow-up results in a lower warm response rate. For example, the warm response rate of the 5th follow-up is 51.6% lower than the warm response rate of the 1st follow-up.
At the same time, the higher the number of follow-ups, the higher the ratio of negative to positive responses. This means that with every subsequent follow-up you burn more and more bridges to get one positive response. For example, after the 6th follow-up, you will have to get eight negative responses to generate one positive one.
We highly recommend you weight the cost vs benefit and not overwhelm your prospects with follow-ups. Give your prospects some breathing space. They probably have good reasons for not responding to you. Getting less warm replies initially is better than the risk of annoying your prospects who might not only unsubscribe from your future emails (and shrink your future pipeline), but also mark your email as spam. This will hurt your sender reputation.
Outbound sales is all about timing, so if your prospect does not get back to you after a few follow-ups, it might mean they are not ready to buy, they are not aware of their problem, they have no budget or they have too much work to deal with right now. Sending yet another follow-up will not change that.
At Growbots we have decided to send only three follow-ups in a sequence. We will then stop the campaign and start a new one after a few weeks (or months even ). We genuinely believe that this will allow us to maintain a good warm response rate and a fairly low negative response rate – keeping our prospects happy. You should try it as well!

A special bonus

As a bonus, we are including statistics on the email follow-up frequency – i.e. how many days you should wait before sending another follow-up. It has been calculated using the dataset from the findings.



  1. The first follow-up has the highest warm response rate when sent after 
4 days from the initial message.

  3. The second follow-up has the highest warm response rate when sent after 3 days from the first follow-up.

  5. The third follow-up has the highest warm response rate when sent after 
2 days from the second follow-up.

Good luck!

Behind the scenes

This report was delivered to you by Growbots. We are the team behind the first platform that streamlines the entire process of getting meetings with new potential customers. We bring together sales prospecting and outreach into one tool, providing our customers with results like:

When you’re starting from scratch:

87 meetings with Fortune 500 brands and $1M deal closed in 1,5 month

case study
When you want to improve your existing process:

10x reduced time spent on prospecting and customer acquisition cost

case study

Want to learn more about our solution?
Request a demo below!


Kasia Kowalska

Content Marketing Manager @ Growbots

Maciej Procyk

Data Analyst @ Growbots

Chris Zawisza

Head of Demand Generation @ Growbots

All data summary

Here you can find a summary of all test we've run in order to write this report. Feel free to share it with your friends and colleagues!

initial message1.24%5.27%4.25
1st followup1.28%6.24%4.88
2nd followup1.01%5.88%5.79
3rd followup0.70%4.46%6.37
4th followup0.69%4.09%5.96
5th followup0.62%3.53%5.66
6th followup0.51%4.19%8.19
7th followup0.44%3.07%6.89
8th followup0.39%2.71%6.87
9th followup0.22%2.20%10.07
10th followup0.16%2.15%13.71