Audience Engagement

The events being done by your recipients. Example: Email opens, link clicks, unsubscriptions, spam complaints, sending a reply, etc.

Audience Segmentation

Narrowing down your audience into smaller groups based on their interests, attributes, activities. Example: Subscribers who have a Gmail address and opened at least one of the emails in the last 30 days.

Black List

A list of email delivery server IP addresses or sender domains that are regarded as unacceptable or untrustworthy and should be excluded or avoided.


The Controlling the Assault of Non-Solicited Pornography And Marketing Act of 2003 is a law passed in 2003 establishing the United States' first national standards for the sending of commercial e-mail. The law requires the Federal Trade Commission to enforce its provisions. Wikipedia

Delivery Server

The email sending servers. A delivery server has at least one IP address.


DomainKeys Identified Mail is an email authentication method designed to detect forged sender addresses in email, a technique often used in phishing and email spam. DKIM allows the receiver to check that an email claimed to have come from a specific domain was indeed authorized by the owner of that domain. Wikipedia


DMARC is an email authentication protocol. It is designed to give email domain owners the ability to protect their domain from unauthorized use, commonly known as email spoofing. Wikipedia

Domain Alignment

Domain alignment (also called identifier alignment) is a mechanism that ensures an authenticated email domain aligns with the domain found in the 'From' header address, which represents the sender's identity.


A Delivery Status Notification (DSN), or simply a bounce, is an automated electronic mail message from a mail system informing the sender of another message about a delivery problem.


A feedback loop, sometimes called a complaint feedback loop, is an inter-organizational form of feedback by which a mailbox provider forwards the complaints originating from their users to the sender's organizations. Wikipedia


A fully qualified domain name, sometimes also referred to as an absolute domain name, is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System. It specifies all domain levels, including the top-level domain and the root zone. Wikipedia

Hard Bounce

A hard bounce indicates a permanent reason an email cannot be delivered. In most cases, bounced email addresses are cleaned from your audience automatically and immediately.

IP Address

An Internet Protocol address is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: network interface identification and location addressing. Wikipedia

List Hygiene

Email hygiene entails cleaning out inactive (cold) email subscribers from your future email marketing campaigns and keeping your remaining list warm with healthy email sending habits.


The Mail From (MFROM) address is the email address that identifies from where the email actually came. It is automatically added to the envelope of the message by the sending mail transfer agent (MTA) before the message is sent. The MFROM is the address to which undeliverable message notices, or bounces, are sent.


Within the Internet email system, a message transfer agent, or mail transfer agent, or mail relay is software that transfers electronic mail messages from one computer to another using SMTP. The terms mail server, mail exchanger, and MX host are also used in some contexts. Wikipedia


A mail exchanger record specifies the mail server responsible for accepting email messages on behalf of a domain name. It is a resource record in the Domain Name System. It is possible to configure several MX records, typically pointing to an array of mail servers for load balancing and redundancy. Wikipedia


A PTR (or Pointer) record is a security tool. Essentially, when you receive an email, your mail server uses the PTR record that comes in with the email message to check that the mail server sending the email matches the IP address that it claims to be using. This is also known as “reverse DNS lookup.”


In computer networks, a reverse DNS lookup or reverse DNS resolution is the querying technique of the Domain Name System to determine the domain name associated with an IP address – the reverse of the usual "forward" DNS lookup of an IP address from a domain name. Wikipedia

Sender Reputation

An email sender reputation is a score that an Internet Service Provider (ISP) assigns to an organization that sends email. It's a crucial component of your email deliverability. The higher the score, the more likely an ISP will deliver emails to the inboxes of recipients on their network.

Spam Complaint

Spam complaints are reports made by email recipients against emails they don't want in their inbox. It's important to understand how spam complaints work, and how to do your best to avoid them, because even legitimate senders get complaints.


Sender Policy Framework is an email authentication method designed to detect forging sender addresses during the delivery of the email. SPF alone, though, is limited to detecting a forged sender claim in the envelope of the email, which is used when the mail gets bounced. Wikipedia