Email Reputation? Sender Score? Spam? Junk? How does sender reputation impact your email deliverability?

You don’t pour your heart into crafting a brilliant, compelling, well-thought-out email campaign just so it can plop into the depths of a spam folder or boomerang back to you. Yet that’s exactly what will happen if you don’t take care of your sender reputation.


“SPAM is taking email, which is a wonderful tool, and exploiting the idea that it’s very inexpensive to send mail.”  –
Bill Gates 

Write amazing email copy, add some groovy imagery, create a spot-on call-to-action, fire off the email campaign to your mailing list and watch customers rolling in – seems rather easy, right? However, your email campaign won’t deliver the desired return on investment if it doesn’t reach the recipients’ inbox or, worse, ends up in the spam folder. This is where sender score and email reputation comes into play.

This article covers the following topics on sender reputation, the spam folder and email sender score:

  1. What is Sender Score?
  2. What is email sender reputation?
  3. How-To: Improving your email sender reputation sender score
  4. How to stop emails going to junk?

Ready to dive in?

In 2021 the projected number of daily sent/received emails worldwide, according to research, is expected to exceed 319 billion. With that said, internet service providers (ISPs) and email service providers will always do their best to protect email users and reduce the clutter to show people only wanted and relevant emails. 

The top two metrics that ISPs and email service providers use to determine which emails will make it to the inbox, go straight to the junk folder and be blocked immediately are sender score and email reputation.

Are your emails struggling to get through? To make it to the inbox, make sure you are on the right side of these spam filters

What Is Sender Score?

A sender score, according to email and deliverability experts, is the numerical representation of your sending reputation determined by measuring your performance across key metrics important to email service providers and, of course, email subscribers. 

Think of your email sender score as a credit score. But, rather than dealing with banks, you are dealing with email service providers. Your sender score sits on a scale of 0-100, with 0 being the worst and 100 the best, and reflects the reputation of your IP address which factors in establishing whether or not you’re filtered out as a spammer.

How To Calculate/Check Your Sender Score?

If you are experiencing a drop in email deliverability and open rates or an increase in bounces rates, there’s a good chance your sender score – and email reputation – are in trouble. However, there are two ways to check your sender score instantaneously – 

According to Return Path by Validity, your sender score is made up of the following reputation metrics – 

  • Complaint rate. It measures the recipients’ complaints against the email you send.
  • Message filtered rate. It indicates if your email was filtered to the spam/junk folder.
  • Infrastructure. It represents the hardware used to send emails.
  • Sending volume. The number of emails sent from your IP over a period of time. 
  • Sender rejected rate. Any email blocked during the SMTP “conversation”. It is usually taken from the incoming SMTP logs of participating ISPs.
  • Unknown user rate. When you send an email to a recipient that never existed or is no longer active they are known as ‘unknown users’.
  • Spam traps triggered. Spam traps are email addresses solely created for the purpose to capture spammers. This metric indicates the number of spam traps hit over a period of time.
  • Blacklists. A list of IP addresses created and maintained by ISPs, anti-spam organisations, spam filtering companies and email service providers to help with the filtering and blocking of spam.

Be advised that online services use a proprietary algorithm utilising a wealth of data powered by email service providers, spam filtering companies and spam trap networks. Ultimately, it’s ISPs and email service providers – through THEIR datasets – that have the final say on whether or not you’re sending “good emails”.

Pro tip: Just getting a “high” sender score doesn’t automatically guarantee all of your email campaigns will end up in the recipients’ inboxes.

What Is Email Sender Reputation?

An email sender reputation is a numeric representation of your sending IP address reputation that email service providers monitor to determine whether or not your emails are spam. It is an essential component of your email deliverability. Basically, ISPs assign email senders a score based on three important reputation factors.

Pro tip: An excellent way of monitoring your email sender reputation is keeping an eye on your email marketing KPIs. A noticeable decline in open rates and lack of engagement might be due to poor email sender reputation or bad sender score.

IP Reputation

Sending unsolicited emails (spam) has been a problem of global proportions and a huge threat to email subscribers and businesses for years. Not even email marketing platforms (like Sendgrid) are protected.

To counter the disturbingly high distribution of spam, ISPs are utilising IP reputation to determine the quality of emails. Way back when, there wasn’t a variety of methods to authenticate a domain address. Thus, ISPs created complex IP reputation models which differed from one another BUT shared the same task – identifying “problematic” IP addresses. Unfortunately, after a while, relying solely on IP reputation to determine email deliverability practice was inefficient because it didn’t consider how different IPs could deliver junk mail with identical content.

Simply put, every email can be traced to an IP address and IP addresses gain IP reputation based on past incidents – i.e. blacklisting, bounces, etc. 

Content Reputation

Advancements in tech have allowed internet service providers to adopt a new approach to measuring the quality of an email – content reputation. 

Content reputation measures the email copy to determine whether the content sent is valuable, non-spammy, non-offensive and of high quality. Specific types of content are clear triggers for ISPs (i.e. attaching a virus, requesting bank details, etc.) and will result in an immediate “spam” flag without questions asked. Furthermore, if your open and click-through rates go down and unsubscribe rates go up, your content reputation will also suffer.

Pro tip: Content and IP reputation go hand-in-hand to help email marketers – and ISPs – gain a better understanding of a sender’s historic email send quality.

Domain Reputation

While IP reputation is based on your sending IP address, domain reputation is based on… you guessed it, your sending domain. Domain reputation represents the overall “health” of your sending domain as interpreted by email service providers (i.e. Gmail. Yahoo!, Outlook, etc.) taking into account factors such as –

  • spam complaint rates
  • spam traps
  • bounce rates
  • engagement rates

The top three factors that affect your domain reputation are – 

  • web domain age
  • domain category (or industry)
  • links to other domains/websites

The awesome team at EmailOut strongly suggests that all its users update their DNS settings (with their respective domain hosting providers) to benefit from DKIM and SPF authentication

Remember, when you are sending an email campaign to the recipients’ email service provider their server will check where the email came from and that it’s properly authenticated. If you don’t update your DNS settings your email will fail authentication and may never reach the intended audience.

Now, don’t you go screaming and crying, alright? It’s not as scary as you might think. EmailOut has a dedicated DNS tool where you will find the records you need to update your DNS settings with. Once you have updated said settings, the platform will “tell” you if it has worked or not.

To take it up a notch, if you want EmailOut to send emails from more than one sender email address or domain, all you need to do is add an alternative email address (you can add as many as you like) then update the DNS settings accordingly.

In this manner, the domain reputation of yourdomain1.co.uk will be kept separate from the domain reputation of yourdomain2.co.uk.

Pro tip: You cannot avoid negative domain reputation by switching email service providers or email marketing software, or using a different sender email aliases.

How-To: Improving Sender Score and Email Reputation

Do you want to –

  • prevent your emails from being spoofed
  • improve your email deliverability
  • ensure that people who signed up to your email lists continue to receive your emails?

If the answer is “Yes!”, you – dearest reader – need email authentication.

What Is Email Authentication?

Email authentication can be an unnerving topic for any email marketer. More often than not, you’ll come across an alphabet soup of different abbreviations and acronyms that will make your head spin. However, certain email authentication methods will help you ensure the security of your email sender reputation. (I’ll tell you all about them in a jiffy!)

Email authentication, technically speaking, is a process that helps identify the sending source (for example, sending domain or IP) of an email so that ISPs will route the email confident of where it came from.

In simpler terms, email authentication is a process set to help you, the sender, prove you are who you say you are (not that J@ne D0e from M1cr0s0ft urgently asking you for your bank details) and that the email you’re sending is not forged/spoofed. 

In other words, email authentication allows email marketing tools to send emails on your behalf AND as your domain.

How Does Email Authentication Work?

There are many ways to approach email authentication, each one with its specific technicalities. However, the general authentication process works as follows – 

  • the sender establishes a policy defining the rules by which emails from their domain name can be authenticated
  • the sender configures its email servers to implement and publish the rules
  • the email server receiving the email authenticates the message by verifying the details of the incoming email against the rules defined by the domain owner
  • the receiving email server takes action based on the results from the authentication process to either deliver the email, send it to the junk folder or disregard it completely

When the receiving email server gets your message it looks for specific information in your email and the Domain Name System (DNS) records (see, you need to update them) of your domain to determine – 

  • the legitimacy and security of your message
  • whether or not it is safe for the recipient to receive
  • if the email came from an authorised source

Email Authentication Methods

Beyond just looking at the sender’s email address, there are four email authentication methods (or standards) ISPs use that email marketers can take advantage of to stop emails going to junk or be rejected by the mail servers.

Sender Policy Framework (SPF)

Sender Policy Framework or SPF is an authentication standard which purpose is to detect falsification of the sender address (return-path header) during the delivery of the email. It’s a DNS record that specifies which IP addresses and/or servers are allowed to send email communications from that particular domain. 

When implementing SPF, always keep in mind that each domain can have a maximum of only one SPF record.

The disadvantage of SPF authentication is that this method alone cannot authenticate the original author of the email. Instead, it authenticates only the source of it (return-path). The best course of action to prevent email spoofing is to combine SPF with DMARC and DKIM.

DomainKeys Identified Mail (DKIM)

DomainKeys Identified Mail or DKIM is an authentication standard focused on detecting fake/fraudulent sender email addresses – email spoofing. Just like an SPF record, DKIM is a TXT record added to a domain’s DNS. It allows the email’s recipient to check if the email message has been authorised by the domain owner. 

Unlike SPF, DKIM uses an encryption algorithm to create a pair of electronic keyspublic and private. The public key is placed in the DNS record, whilst the private key remains on the servers it was created on (i.e. your mail server).

To implement DKIM, you are required to update your DNS setting just like with SPF.

Pro tip: This tool will be very useful for generating both public and private DKIM keys.

Domain Message Authentication Reporting and Conformance (DMARC)

Domain Message Authentication Reporting and Conformance or DMARC is an email authentication standard focused on handling the problem of email spoofing by protecting both the sender and the recipient. Your DMARC record instructs the receiving server not to accept an email if it fails DKIM and SPF checks.

Is DMARC enough for email authentication? On its own – no. DMARC needs SPF to work.

Your DMARC record is published with your DNS records. It “tells” the receiving server not to accept an email if it fails DKIM and SPF (among other checks). 

Pro tip: All the leading ISPs have already introduced DMARC checks on their receiving servers.

Brand Indicators for Message Identification (BIMI)

Brand Indicators for Message Identification or BIMI is an open standard allowing businesses to verify their identity and be easily recognised in recipients’ inboxes. Similar to SPF, DKIM and DMARC, BIMI is a text record that lives on your servers. It works alongside SPF, DKIM and DMARC to show email service providers you are you. Some even call this authentication standard DMARC 2.0.

To enable BIMI, the following requirements must be in place –

  • a DMARC record with a ‘quarantine’ or ‘reject’ policy
  • recognition as a bulk sender and a good sender reputation
  • another DNS record called BIMI Assertion Record. It’ll contain the link to the image (SVG format) that is going to be used

How To Stop Emails Going To Junk?

From newbies to email marketing gurus, we’ve all faced email deliverability issues. Your emails can accidentally end up in the spam folder and it’s frustrating. But… with the help of a few practical tips and tricks your “how to stop my email going to junk” problem can be easily solved.

  • organically build your email list
  • always use double opt-in
  • use email authentication
  • maintain email list hygiene
  • be compliant with email marketing laws
  • monitor email marketing KPIs
  • follow email design best practice
  • send relevant content
  • ask recipients to whitelist your domain
  • don’t link to shady websites
  • avoid spam trigger words
  • use accurate sender information
  • add a physical address to all emails
  • always add an unsubscribe link
  • use reputable email marketing software
  • send emails frequently
  • monitor your email sender reputation

Ready for your emails to land in the inbox again?

Final Thoughts

Your email reputation is in YOUR hands. If you send wanted and relevant emails with the right message to a consenting audience and at the right time, your sender score and email sender reputation should be fine. Just don’t get slouchy! 

Use all the tools and techniques at your disposal to get a perfectly accurate picture of how email service providers view your email. Then, use the data to improve your email sender reputation, sender score and, ultimately, your email deliverability.

Gaining a good email sender reputation and sender score requires a lot of time, patience and, of course, a bit of strategising. Destroying it, however, needs just a few poor decisions and a couple of bad judgement calls. 

Highly recommended further reading – 

1) Writing Marketing Emails 101
2) Why Is My Email Going To The Spam Folder?
3) 10 ‘Must-send’ Marketing Emails
5) Email Engagement: Paramount For Email Deliverability
4) Email Marketing Campaign Checklist (PDF version here)

[EmailAddress]
[EmailAddress]
[YouTube Music Video]
[YouTube Music Video]