What is sender score and why does it matter ?

Sender score email

Most of the emails you send today are spam. This is a fact. You might have noticed some of the emails you sent never arrived at the recipient. Or maybe you received a complaint from a customer that received 20 emails from your brand in the last week. The chances are, that most of them were considered spam by your customer’s email provider. A sender score is an email metric created by ISP (internet service provider) to help them evaluate the trustworthiness of a sender.

Your sender’s reputation is one of the main factors in the deliverability of your emails. Your reputation is important because it determines whether your emails will arrive in the recipients’ inbox or are filtered to their spam folder. So your sender’s reputation directly affects whether your email marketing campaigns successfully reach your target audience.

A low sender reputation equates to a low probability that your emails will reach the inbox. So it is essential to understand your sender’s reputation and how to improve it. We need to look into a number of email metrics that can negatively affect your sender reputation, such as your email sending history, spam complaints, high bounce rates, and low open rates.

What is your Sender Score?

Your Sender Score is a measure of your sender reputation on a scale of 0-100 usually calculated on a 30-day rolling average. Ultimately, it is an attempt to measure the rate your emails arrive in the inbox, not the spam folder. Sender Scores apply to IP addresses or domains.

The higher the Sender Score, the better your email deliverability rate. Though, be aware that because it is measured over 30 days, the score will change from one emailing campaign to another.

ISPs look at your Sender Score, so it is crucial to maximize it for successful email deliverability. 

How to measure your Sender Reputation?

It is important to measure your reputation as a sender. As we have seen, this can have a direct impact on how your emails are treated by recipients. Email providers’ spam filters often use your reputation to decide whether your emails should be delivered to recipients’ inboxes or not. 

Here are some of the most common tools used to measure your sender score:

Sender Score of Return Path

Sender Score is a free email reputation evaluation service offered by Validity that allows you to obtain the score and evaluation of an IP address. The score is between 0 and 100. The higher the score, the more likely your emails will be delivered to your recipients. 

Talos Intelligence Group by Cisco

Talos Intelligence Group allows you to measure the Sender Reputation of an IP address, from -10 (for the worst) to +10 (for the very best), and also check if it is blacklisted. Their scores group ISPs into Good, Neutral, and Poor.

Google’s Postmaster Tools

Postmaster Tools is a free tool provided by Google that allows you to access different information about the reputation of your domain. This tool is very useful if your recipients are mainly on Gmail. It allows you to know how your domain is perceived by Google.

Factors influencing your Sender Score

Spam reports

Spam reports are very important in email deliverability and influence your Sender Score. If you receive a lot of spam complaints when sending emails, your Sender Score will be negatively effected, dropping lower and lower until improvements are made. This can lead to difficulties with the deliverability of your emails.

Bounce Rate

The Bounce Rate will also have a negative effect on your Score. Hard bounces, in particular, can be detrimental. They indicate that an email address is no longer valid, which can happen for several reasons, but among the most common are typos in emails, or a deactivated email address.

Spam traps

Spam traps capture email addresses that are not valid. There are several types of spam traps, including:

  • Virgin or pure spam traps
  • Recycled email addresses
  • Invalid email addresses

  • Email infrastructure

    Your email infrastructure is the technical framework of your hardware and software, sitting behind the sending of your emails, campaigns, newsletters, etc. This infrastructure plays an important role in your Sender Score.


    If your IP address is blacklisted, your email communications will be systematically blocked by ISPs. Blacklists are directories of IP addresses and domain names that have been identified as spammers. For domain names, this means that emails sent in the name of your company will most likely be considered as spam.

    ISP bulk rate

    The ISP bulk rate is the percentage of emails that end up in the spam folder of your recipients. This rate is defined by the ISPs.