We hear about deliverability in the exciting world of email, but we do not always fully understand it. Just like the credit score you get as soon as you open your first credit account, you know some facts like paying your bills on time will help you maintain a good banking reputation. What actions, though, make you lose or gain points, and by how many points exactly?

We just know that reputation is all based on behaviour and patterns, past or present. The rules change from one person to the other for millions of reasons. If you can wrap your mind around this concept, deliverability should be easier to understand. Let’s talk about deliverability’s most important ally: email authentication

What is Email Authentication?

Authentication comes to mind when we talk about deliverability, as it is one of the first things you should do before sending a campaign to your audience. It is also only done once before you start using any new tool that will be sending emails with your domain-based email address. 

Please note: that this is not the same as confirming your email address with your email marketing tools. 

Authenticated emails allow you to take responsibility for the emails you send, to whom, and the content within them, which in return helps or hurts your deliverability. ESPs and ISPs use authentication to prevent fraud, confirm the sender’s identity, and tell you apart from spammers/phishers. 

A metaphor from the banking sector:

If we use banking imagery to understand deliverability, imagine authentication as being those two forms of identifications you need to show a bank teller. If you have a long-term relationship with an excellent track record, your bank may give you what you ask for, even if you don’t have two forms of identification. They may turn you down if you do not have a good reputation or one at all. 

Identities can be stolen, and it is something that can occur even with domain authentication (Common phishing examples include fake PayPal emails, tax return scams, etc.). 

Authentication standards

To prevent identity fraud in email, authentication options have been created. The most commonly used forms of authentication are SPF, DKIM, DMARC, and BIMI. Briefly explained:

Sender Policy Framework (SPF)

SPF is a form of email authentication that validates an email message that has been sent from a mail server you have given permission in order to detect forgery or prevent spam.

DomainKeys Identified Mail (DKIM)

DKIM verifies that an email message was not forged or altered and that you sent it. By implementing it, you are helping keep your subscribers safer and improving your email deliverability.

Domain-based Message Authentication, Reporting & Conformance (DMARC)

DMARC is a form of email authentication and, most importantly, a reporting tool. It allows you to control how you handle emails that are not authenticated with SPF or DKIM. You have three settings you can choose from: none, quarantine, or reject. The first one will report to you that an unauthenticated email was sent but won’t affect the email’s placement. A “quarantine” policy will put an unauthenticated email in spam or junk. If you implement a “reject” policy, any unauthenticated emails will be denied by receiving inboxes. 

In layman’s terms, it means you get to control what happens to unauthenticated emails to protect your brand and subscribers from fraudulent emails. All the tools you use that send emails with your domain-based email address must be authenticated with SPF and DKIM before implementing DMARC policies to not block your own emails from landing in your audience’s inbox. 

Authentication & Reputation

It is important to remember that you need to authenticate your sender domains with all the tools that send emails on your behalf. It is the first step to helping you build and maintain your reputation, and most importantly, you aren’t putting a stick in your wheel and making it harder to land in the inbox. So, what else can you do that will help your deliverability and your domain’s reputation? 

Domain Reputation

Your domain’s reputation is an essential factor in deliverability. Even if your subject line is capitalized and has many exclamation points, a good reputation will help your email land in the inbox. Yelling at your audience or using “known spam words” is not a great marketing strategy, but spam filters look at so much more. 

Spam filters

Spam filters in your inbox help protect you from unsolicited emails, malware, phishing attempts, and so much more. A domain’s reputation is a strong factor that can help influence the decisions made by spam filters. 

Spam filters look at your past behavior to determine what to do with your email. If you are sending to your audience, which in return open and interact with your email positively, they are more likely to help your future emails land in the inbox. On the other hand, if you send emails to people who do not engage with your campaign or you get many spam complaints, they will be more strict on your inbox placement in the future. 

Stick to deliverability best practices

Spam filters also compare your emails to those of spammers. The percentage of spam being sent in a day is much higher than those of legitimate nature (DataProt, 2021). There is a bigger pool of spam emails to analyze, making it easier to compare your emails to those of spammers instead of others in your industry if you do not follow best practices. 

For example, if you buy lists, it is easy for spam filters to detect this behavior and penalize you. You will most likely send your campaign to spam traps, which in return will yield a high bounce and spam rate. You want your audience to open your email, read it, click on links and even perform actions beyond your campaign instead. All those actions help teach spam filters what each member of your audience thinks of you. 

Delivery vs. Deliverability

Delivery and deliverability get used interchangeably sometimes, but they are two different terms to an email specialist. 

Delivery is the number of emails sent that were accepted by your subscribers’ inbox providers’ servers. On the other hand, deliverability is all about where your emails land: the inbox or the junk/spam folder? 

The quality of your list will impact the delivery and deliverability of your email. If your list consists of only real email addresses that can accept your email, your email’s delivery will be 100%. 

Bounces & Complaints

High bounce and spam complaints will impact your delivery and deliverability as well. A bounce is created when an email address cannot accept your email or doesn’t exist, which affects your delivery rate. Long term, consistent high bounce rates will affect your deliverability as it shows spam filters that you don’t have good list hygiene. A high spam complaint affects your deliverability, as a human interaction creates it. It shows the spam filters that your emails are unsolicited. 

It is always better to have someone unsubscribe than to hit the spam complaint button. Please don’t gamble your reputation by making it challenging to unsubscribe from your emails.


Delivery is calculated by the number of emails accepted by an email address’s inbox. Deliverability, on the other hand, goes hand in hand with your reputation. A bad reputation doesn’t mean that every single email you send will land in the junk/spam folder, but it sure isn’t anywhere close to 100%. Don’t forget, just like there are thousands of factors that affect your credit, there are just as many affecting your deliverability. Use this guide to get started on your journey to better reputation and deliverability.