Email Authentication: A Valuable Step in Deliverability

What is Email Authentication?

Email authentication, otherwise called domain authentication, is a way of maintaining your reputation as a sender and securing ISPs’ (Internet Service Providers) confidence in your email. In different terms, authenticating your email is a process of demonstrating the trustworthiness of your email. 

Authentication is also a way of combating scam and phishing schemes that may otherwise harm your business or campaigns. Many scammers have developed practices that target customers into sharing personal information under the guise of a trusted brand.  

Why is Email Authentication Important?

To protect the interests of email users, mail servers examine the legitimacy and validity of emails. They do this in a number of ways but mail servers essentially explore a sender’s reputation, email engagement with previous sends and whether the email is actually coming from the stated sender.

It’s important to authenticate your email to avoid seeing your emails ending up in spam, to improve your overall deliverability and develop your reputation as a sender.

The Mechanisms Involved in Email Authentication

There are a few primary tools involved in email authentication. 

Sender Addresses

One of the most straightforward things that you can do to validate your email is to be undeviating in the addresses used to send out emails. Customers open emails from brands and accounts they trust. Finding inconsistencies in the sender addresses of branded emails might spark scepticism or lead customers to trust in a possible phishing scheme. The same goes for domains – try to be consistent in the domain you use to send out emails. 


Simply put, the Sender Policy Framework is used to determine which IP addresses can send out emails from any particular domain. A DNS, or domain name system, is a list created by a sender to authorize various IPs to send out mail from their domain. ISPs then use this list to authenticate emails at an SPF level. 


Another form of authentication is DKIM, or DomainKeys Identified Mail. DKIM is basically an encrypted signature and key that a sender adds to their email. Only those who have access to DNS records can put in place a DKIM. What a DKIM does is that, when decrypted, receiving mail servers use it to verify that the mail was not forged or altered in its delivery process.   


DMARC, or Domain-based Message Authentication, Reporting and Conformance, is another authentication standard. DMARC is a policy that empowers senders to indicate to receiving mail servers that their messages are protected by both SPF and DKIM. This is crucial in circumstances when your SPF and DKIM do not pass a mail server’s authentication check. A sender’s DMARC policy specifies how mail receivers should handle the incoming message – such as blocking the message or placing it in a spam folder.  If you are interested in learning more about DMARC, this post discusses it in greater depth.

Inboxroad and Authentication

So, where does Inboxroad come in when it comes to email authentication? The following points are related to the role Inboxroad plays in your email authentication:

  • SPF: by allowing Inboxroad IPs and domains to their list of permitted senders, our customers ensure that our delivery will not face rejection by receiving mail servers.
  • DKIM: Inboxroad creates a pair of domain keys – public and private – for our customers to add to their DNS records.
  • DMARC: We advise customers on their DMARC policy. It is very flexible and can be adjusted according to customer needs. Some available DMARC policies include,
    • none: this allows the message to reach recipient mailboxes, even if its authentication fails
    • quarantine: the email will land in the spam folder if it does not pass the authentication
    • reject: the email will not be delivered should the authentication fail.