Email Deliverability 101: Terminology and Lingo

Email Deliverability Simplified | The Blog

email deliverability

Being a successful email marketer in today’s digital landscape is challenging — with continually evolving regulations and changes in ISP requirements, ongoing learning is a must.  Keeping up with all the changes, vocabulary, and best practices in email deliverability can be a huge undertaking, but don’t worry because we have your back!

You can check out our blog archives for best practice tips on email deliverability, but today we’re going to cover the basics — dispelling the terminology and lingo of email deliverability.

Delivery vs. Deliverability

First things first, let’s address the difference between the terms “delivery” and “deliverability” (also known as “inbox placement”).

  • Delivery (or Acceptance Rate) refers to whether or not your target recipient receives your email.  If we say your delivery was successful, then that means your email made it email address you sent it to (keep in mind that this could be the inbox or spam folder — basically, it wasn’t kicked back as ‘undeliverable’).
  • Deliverability (or Inbox Placement) refers to where your email lands once the message is received.  If it was allowed to hit your target recipient’s inbox, then you’ll have a positive inbox placement or email deliverability rate.  If it went to spam, then your deliverability rate will be lower.


There is often confusion around the terms ISP and ESP for new marketers, so let’s tackle the difference between these two terms next.

  • ISP (Internet Service Provider) is a company that provides mailboxes (email addresses) to users as part of their service offerings.  Typically these are cable or internet providers like AT&T, Spectrum, Comcast or Verizon.
  • Inbox Providers are often confused with ISPs; however, these typically aren’t paid services, but rather companies offering free webmail accounts.  These companies include Gmail, Yahoo, and Outlook.
  • ESP or Email Service Providers are the companies who use their platforms to send commercial or transactional emails on another company’s behalf.  These include companies such as MyEmma, Constant Contact, SalesForce/Pardot, or MailChimp.

Other Terminology Basics

Now let’s dive into a few of the basic terms you’ll encounter as an email marketer:

    • Black List(s) are lists that ISPs, Inbox Providers, or ESPs create to identify potential spammers.  Companies that find themselves on these lists will see their emails and newsletters automatically being delivered to Spam Folders, if not potentially blocked altogether.  Check out our blog on Black List 101 to learn the steps you can take to avoid these lists or get your company removed should you find yourself on one of them.



    • Click-through Rate is a metric showing how many people clicked on a link within an email you sent.  This is a huge metric because it means they didn’t just view your email or see a preview of it, the target user actually engaged with your email.


    • DKIM (Domain Keys Identified Mail) is your domain’s digital signature.  Basically, it associates a domain name with an email, allowing an organization to claim responsibility for emails being sent.  It creates a sense of authenticity to an email and gives a recipient the ability to believe that the email message is from who it says it is from.


    • Double Opt-in is a best practice and gives marketers the ability to email or market to users.  For a target recipient, it gives them the ability to say “yes, I really want emails from this company.”  Not only does a potential recipient click the single opt-in field, but they also must click the confirmation button they’ll receive via email to double opt-in to being on the company’s email list.


    • Hard Bounce is a permanent failure of an email to reach its destination.  Typically this is caused by an invalid, blocked, or non-exist email address having been used.  Best practice is to remove these email addresses from your email list when a hard bounce is received.


    • Open Rate is the percentage of recipients who opened your email.  While this used to be looked upon as the holy grail of statistics for marketers, more creditability is being given to click-through rates since email preview can impact this metric and give a false sense of performance or user engagement.


    • Read Length is how long a user opens and “reads” your email until they close it.


    • Sender Policy Framework is your DNS (Domain Name Server) record that says an IP or domain can send an email on behalf of your company.


    • Single Opt-in is the standard “let us know you want to be on our email list” checkbox marketers include on their landing pages, newsletter sign-up, and webinar sign-up pages.  In order to stay compliant, you always want to include an opt-in when you gather an email address.  Want to be super compliant and decrease your odds of being marked as spam?  Then consider incorporating a double opt-in process into your email gathering campaigns.


    • Soft Bounce is a temporary status stating that your email cannot be delivered at this time. Typically it has to do with something like the server is unavailable or the recipient’s inbox is full.  However, if after 72-hours it still cannot be delivered, then it will turn into a hard bounce which will count against your blacklist or spammer score…so don’t disregard these metrics.


    • Spam is what we call email messages that we don’t ask for or didn’t opt-in to receive.  It’s the junk mail of the cyber world.


    • Spam Report is when a user clicks the ‘spam’ button, telling an email provider that the email they just received is spam.  If too many users mark your emails as spam, you’ll find yourself blacklisted.


Now that you have the basic lingo down, here are a few more of our blogs we think you might find useful in getting your footing and strengthening your knowledge as a successful email marketer:

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