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19 EMAIL DELIVERABILITY TERMS to meditate for better inbox placement!!

A hundred things go into the details of email delivery. With various inbox management tools available, it’s gotten more difficult to reach the subsc...

A hundred things go into the details of email delivery. With various inbox management tools available, it’s gotten more difficult to reach the subscriber’s inbox. is extremely inevitable. Despite following the email design best practices, email delivery has always been a conundrum for many. We bring you a list of 19 email deliverability terms that would help you understand email delivery better:

Email Metrics

1. Open Rate

A percentage indicator of how many people view or open the commercial electronic mail you send out. A better estimate of deliverability can be achieved by considering the click-through rate along with it.

2. Acceptance Rate

Acceptance rate is a percentage indicator of emails that are accepted by the email server. However, this cannot gauge deliverability accurately as it’s not necessary that every accepted email lands into the inbox.

3. Read Length

Read length is the time duration between: when a subscriber opens an email and up to he/she closes it.

4. Sender Score

It is an indication of the trustworthiness of an email source. Sender score represents the rank of an IP address against other IP addresses. Even if your emails are delivered, a poor Sender Score could imply that they aren’t reaching all your recipients’ inboxes.

5. Hard Bounce

Hard bounces are emails that permanently fail to be delivered as a result of stale, invalid, blocked or non-existent domain or email addresses. Hard bounce has a very negative impact on your deliverability.

6. Soft Bounce

Soft bounces are emails that temporarily fail to be delivered to the inbox because of reasons such as an unavailable server or full inbox. Soft bounces also affect your deliverability up to a certain extent, as if an email stays undelivered for 72 hours, it automatically gets registered as a hard bounce!

Remember, unless you measure, you can’t improve!

List Building

7. Single Opt-in

Single opt-in generally has a check box in the form or capturing just the reader’s email address which automatically adds the address to a live email list. Chances of incorrect and invalid email addresses are higher in the single opt-in method of list building, affecting your deliverability metrics.

email deliverability terms- opt in

8. Double Opt-in

The more preferred opt-in method, this one includes sending an email with a link to confirming the recipient’s email address, after the initial opt-in. This facilitates a clean list with valid email entries only and hence recommended for a better deliverability.

email deliverability terms- double opt in

Remember “A small list that wants exactly what you’re offering delivers better than a bigger list that isn’t committed.”



An abbreviation for ‘Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003’, is a law applicable to all businesses that establishes the rules for commercial email and commercial messages sending, gives recipients the right to have a business stop emailing them, and outlines the penalties incurred for those who violate the law

10. Spam.

Spam, also known as junk email or unsolicited bulk email (UBE) involve nearly identical messages sent to numerous recipients by email. Spam accounts for 14.5 billion messages globally per day which is 45% of all emails.

11. Spam Report

When someone you sent an email to labels or marks it as spam, is called a spam report.

12. Spam Trap

A repeated hard bounce from the same dead email address automatically identifies that particular email address as a spam trap and would report the email sender as a spammer. This is where regular list hygiene plays a vital role towards email deliverability.

13. Honey pot

As the name suggests, honey pots are dummy email addresses planted to lure spammers and identify them thereby to be reported.

14. Graymail

Graymail constitutes emails and newsletters which a subscriber has legitimately signed up to receive, but eventually lost interest from. Basically, unwanted emails that do not deem fit to the definition of spam.

15. Ham

Ham is desired email that cannot be regarded as spam. Who denies Ham after all?

16. Blacklist

Email Blacklists are a compilation of IP addresses and domains flagged as “known” sources of spam, collected over a course of time, based upon email recipient’s spam complaints, increased bounce rates and other spam-traps. It’s best to stay away from blacklists for a better deliverability.

17. Whitelist

It is a list of commercial mailers approved to send through a certain ISP. Being on a whitelist increases your chances of exemplary email deliverability.

Email Validation

18. DKIM

Domain Keys Identified Mail, also known as digital signature, is an email validation method for associating a domain name with an email message. This allows an organization, role or person to claim responsibility for the email, giving recipients an assurance that the email was created by a known sender and was unaltered in transit.

19. Sender Policy Framework

SPF is a simple email validation system designed to detect email spoofing. It provides a mechanism that allows mail exchangers, a check to see that the incoming mail from a domain is being sent from an authorized host.

Any deliverability terms we missed that you think are essential? Write to us in the comments below! 🙂

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Kevin George

Kevin is the Head of Marketing at Email Uplers, one of the fastest-growing full-service email marketing companies. He is an email enthusiast at heart and loves to pen down email marketing content. You can reach him at or connect with him on LinkedIn.



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