Deliverability 101

Deliverability, also known as inbox placement, is a step before the usual open and click-through metrics that we marketing professionals determine our success by. 

What is the difference between optimum and poor deliverability? 

Optimum deliverability means that the contacts you are sending to, are at the very minimum getting the opportunity to open and interact with your email because it successfully arrived in their inbox. At that point it’s up to each recipient to choose whether they then open and interact with your email.   

Poor deliverability is when the contacts you are sending to, never even get the chance to open or interact because email does not land in their inbox to begin with. In some cases, like due to a blocklisting, it may not even land in their spam/junk folders. In these scenarios, something went wrong along the way, on your emails journey to their inbox.  

To achieve optimum deliverability there are four important factors that you need to consider: 
1. Identity 
2. Reputation 
3. Content 
4. Measurement 

Identity 

The recipient’s mailbox provider needs to be able to confirm your true identity as the sender and differentiate you from spammers. Authentication protocols usually include DKIM, SPF and DMARC. 

• SPF – Sender Policy Framework – A Domain Name Server (DNS) record that says an IP or domain can send email on your behalf. SPF enables the owner of a domain to specify which mail servers are authorised to send mail on its behalf. The receiving mail server will check the sending server’s identity against the SPF record and will accept or reject it based on the result. 

• DKIM – DomainKeys Identified Mail – Also known as “digital signature,” this is a method for associating a domain name with an email message, allowing a person, role, or organisation to claim some responsibility for the message. A digital signature gives recipients a reason to believe the email message was created by a known sender and was not altered in transit. 

• DMARC - Domain Message Authentication Reporting and Conformance – Ensures that emails meet SPF and DKIM requirements before they are delivered. 

If you can’t prove your identity, or your recipient’s email address or domain name aren’t valid, or even if your IP address/domain has been blocked, then your email is likely to bounce. This means it can’t be delivered to the recipient’s email address. 

A Hard bounce is a permanent failure to deliver an email usually due to the email address not existing, being invalid, or being blocked. Email addresses that result in hard bounces can negatively impact deliverability and should be removed from your email lists. 

Reputation 

An email sender reputation is a score that an Email Service Provider (ESP) assigns to an organisation that sends email. It’s a crucial component of your email deliverability. The higher the score, the more likely an ESP will deliver emails to the inboxes of recipients on their network. If the score falls below a certain threshold, the ESP may send messages to recipients’ junk/spam folders or even reject them outright. Several factors can go into determining the score, including: 

• The amount of email sent by the organisation 

• How many recipients mark the organisation’s emails as spam or otherwise complain to the ESP about the messages 

• How often the organisation’s emails hit spam traps 

• The organisation’s inclusion on different blocklists 

• How many of the organisation’s emails bounce because they were sent to unknown users or for other reasons 

• How many recipients open, reply to, forward, and delete the organisation’s messages, as well as click the links found in them 

• How many recipients unsubscribe from the organisation’s email list 

Each ESP decides which factors to include in its sender reputation and how heavily it weights those factors when calculating the reputation for each organisation that sends email to some of its users. A sender could have varying reputation scores for different ESPs. If a sender has multiple domain names and sends email from different IP addresses, each one will have its own sender reputation. 

Content 

As marketers, this is the part of the email journey that we dedicate the most time and attention to.  Crafting our subject lines, agonising over our text and calls to action aiming to create a beautiful engaging email that our recipients will love. Avoiding overtly salesy language and spammy content with crazed punctuation or all CAPS we all recognise as best practice, but the best way to really see how well your email would perform and the words and phrases that help or hinder the inbox position is to use a forensic tool – like e-shot’ email Forensics – where you can benchmark and analyse your mails so you aren’t sending blind. 

Measurement 

With email Forensics you can review these elements before you send your message out into the big wide world. With the insights you can get from your email Forensics you can review the key elements of deliverability, content and infrastructure when sending Test emails, so you can be confident your email will hit the mark before you hit send. The new reporting is fully integrated with the e-shot platform, so you can see all the information you need in one place. Within Forensics you can review any potential content or infrastructure issues, with the dashboard highlighting any areas requiring attention or with scope for improvement. 

With our added Forensics insights you can test your email and understand your deliverability at the click of a button so you can continually optimise your campaigns, and improve your results.

Last updated: August 2026