Email Marketing: 20 Deliverability Terms and Definitions

Email Marketing Terms & Definitions

Email Marketing Terms You Should Know To Improve Deliverability

Email marketing starts with deliverability. Deliverability is a partnership between your firms I/P domain reputation, your email account, and your subscriber's email provider. Many circumstances determine how your email is filtered when it is received by an ISP. The determining factor on whether your email marketing messages are delivered into an inbox or spam folder is your IP/domain reputation.

A combination of factors determines your IP/domain reputation. Research has shown that subscriber engagement, limiting negative metrics, authentication and content all play a role. What follows is a list of twenty terms you might encounter when using a mail service like MailChimp or Drip to send your marketing emails. Understanding the definitions of these email marketing terms will help you to ensure that your email marketing drip campaigns and newsletters are reaching your audience.


This is a list of addresses of known spammers or spam friendly servers. If your address ends up on this list, your email will not go through.


This is an acronym for the 2003 law (Controlling the Assault of Non-Solicited Pornography and Marketing Act Law). This law outlines the rules for commercial email and establishes requirements for all commercial messages. It provides email recipients with the right to be removed from your list and lays out consequences for any violations of the law.


Domain names refer to locations of servers and devices connected to the Internet. A domain name can represent many different IP addresses.

Domain Name System (DNS)

DNS is the Internet service that interprets domain names as numerical IP addresses.

DomainKeys Identified Mail (DKIM)

DKIM is designed to prevent email spoofing. Spoofing is when someone pretends to send email from your domain when they really aren't. DKIM uses cryptographic authentication, which means the records generated are unique to you and your domain.

Double Opt-In

When a double opt-in is used, a user is sent an email with a confirmation code after opting-in to your mailing list. They must click the link to confirm their subscription. This method is the best way to build a healthy email list.

Email Service Provider (ESP)

ESP provides the platforms used to send commercial and transactional emails on your behalf.

Hard Bounce

A hard bounce means that an email address is invalid and should not be resent. The email may belong to an unknown user, the contents of your email may have triggered their spam filter, or the server may have seen too many contacts marking your email as spam. When a contact's email returns a hard bounce, they will be marked and removed next time you include them in a mailing.

Internet Service Providers (ISP)

ISPs provide mailboxes to end users as a part of their paid service. These are typically your cable or Internet providers like Comcast or Verizon.

IP Address

An IP address is a number that is unique to each device that is using the Internet. IP stands for Internet Protocol. Similar to how a street address helps you find a building, an IP address helps computers find each other online.

Open Rate

This is the percentage of recipients that opened your email. When someone clicks on an email, an image pixel embedded in the email loads and its counted as an open.

Sender Policy Framework (SPF)

SPF was created to protect against sender address forgery. That's where spammers pretend to send emails as if they were you. An SPF record in your DNS settings gives email providers something to check to confirm that emails are actually sent by you.

Sender Score/Reputation

This is your rating as an email sender. Return Path's sender score tool is a free rating tool that rates your outgoing mail server IP on a scale of 0-100. It's used by mail servers and allows them to quickly sort email IPs and decide how to handle your email. A score of +90 is considered a good sender score.

Single Opt-In

With a single opt-in, when a user fills out a form requesting email on your website, and they are immediately added to your list. That is a single opt-in. (See Double Opt-In)

Soft Bounce

A soft bounce means that your email temporarily failed to reach its destination. Your email will be resent periodically for 72 hours until it is either delivered, or it becomes a permanent fail. Recipients that return soft bounces are still eligible for future email delivery.

Spam Complaints

Spam complaints are the contacts that are marked your email as spam. Email recipients that mark your email as spam are automatically unsubscribed from all of your emails. Be aware - “Marked as Spam” is not the same as email going into a bulk email or spam folder.

Spam Trap

A spam trap is a planted email address designed to catch spammers. For a time, email that hits a dead email address will hard bounce. When an email server sees continued traffic going to a dead address, they can turn that address into a spam trap, accept the email and then report the sender.


This is the opposite of a blacklist. This designates your server as spam free. It's often used to mark whether the email from specific senders can be trusted. This can override some of the filterings that may exist from the ISP. Whitelisting is possible with some ISP's.  While this is not a guarantee to end up in the receiver's inbox, a sender might receive a delivery preference so long as they stay within the guidelines of the program.

Email Marketing Only Works If It Reaches An Inbox

These email marketing terms can help you to improve your email deliverability. Understanding them can help you to focus on areas that may impact your marketing efforts and institute improvements. It's especially important to understand the laws surrounding marketing emails like the CAN-SPAM act. We use email service providers like MailChimp and to create email marketing campaigns and e-newsletters because of their stellar deliverability reputation.