Email Marketing Glossary

A list of key email marketing terms and phrases.


A/B split

A test to compare two different versions of an email. In particular, an email list is split into two groups: half is sent one version of the email, while the other half receives a second version.

Above the fold

The part of an email message or Web page that is visible without scrolling. Material in this area is considered more valuable because the reader sees it first. Refers to a printing term for the top half of a newspaper above the fold. Unlike a newspaper, email and Web page fold locations aren’t predictable. Your fold may be affected by the users’ preview pane, monitor-size, monitor resolution, any headers placed by email programs such as Hotmail, and other factors.

Affirmative consent

An active request by a reader or subscriber to receive advertising or promotional information, newsletters, and so on. Generally affirmative consent does not include the following — failing to uncheck a preselected box on a Web form, entering a business relationship with an organization without being asked for separate permission to be sent specific types of email, or opting out.


An automated process that verifies an email sender’s identity.


Automated email message-sending capability, such as a welcome message sent to all new subscribers the minute they join a list. It may be triggered by joins, unsubscribes, all email sent to a particular mailbox. The autoresponse may consist of more than a single message —it can be a series of date- or event-triggered emails.


A list developed by anyone receiving email, or processing email on its way to the recipient, or interested third-parties, that includes domains or IP addresses of any emailers suspected of sending spam. Many companies use blacklists to reject inbound email, either at the server level or before it reaches the recipient’s in-box.


A message that doesn’t get delivered promptly is said to have bounced. Emails can bounce for different reasons: for example, the email address is incorrect or has been closed, the recipient’s mailbox is full, the mail server is down, or the system detects spam or offensive content. See hard bounce and soft bounce.

Bounce handling

The process of managing email that has bounced. Bounce handling is important for list maintenance, list integrity and delivery.

Bounce rate

Also return rate: Number of hard/soft bounces divided by the number of emails sent. This is an inexact number because some systems do not report back to the sender clearly or accurately.

Bulk folder

Where many email clients send messages that appear to be from spammers or contain spam, or are from any sender not in the recipient’s address book or contact list.


Popular name for the U.S. law regulating commercial email, updated in July 2008. (Full name: Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003)


An email server function that forwards all questionable email to a single mailbox. The catch-all should be monitored regularly to find misdirected questions, unsubscribes or other genuine live email.


A segment of your list that receives different treatment specifically to see how it responds versus the control (regular treatment.)


How many subscribers leave a mailing list (or how many email addresses go bad) over a certain time, usually expressed as a percentage of the whole list.

Click-through rate (CTR)

CTR is calculated by dividing the total number of clicks an email link receives by the number of emails sent. It is used by marketers to measure the success of online marketing campaigns

Confirmed opt-in

Inexact term that may refer to double-opt-in subscription processes or may refer to email addresses which do not hard bounce back a welcome message.


An arrangement in which companies collecting registration information from users (email sign-up forms, shopping checkout process, etc.) include a separate box for users to check if they would also like to be added to a specific third-party list.


Cost per Action (also can be Acquisition). A method of paying for advertising, or of calculating equivalent results from other payment models.


Cost per Click. A method of paying for advertising. This is different from CPA because all you pay for is the click, regardless of what that click does when it gets to your site or landing page.


Cost per Thousand.

Delivered email

The number of emails sent minus the number of bounces and filtered messages. This is a highly inexact number because not all receiving ISPs report accurately on which emails didn’t go through and why not.

Delivery tracking

The process of measuring delivery rates by format, ISP or other factors and delivery failures (bounces, invalid address, server and other errors). An inexact science.


An anti-spam software application being developed by Yahoo and using a combination of public and private “keys” to authenticate the sender’s domain and reduce the chance that a spammer or hacker will fake the domain sending address.

Double opt-in

A process that requires new list joiners to take an action (such as clicking on a link to a personal confirmation page) to confirm that they do want to be on the list.


Email Change of Address. A service that tracks email address changes and updates.

Email address

The combination of a unique user name and a sender domain. The email address requires both the username and the domain name.

Email client

The software recipients use to read email, such as Outlook Express or Lotus Notes.

Email Domain

The portion of the email address to the right of the @ sign.

Email filter

A software tool that categorizes, sorts or blocks incoming email, based either on the sender, the email header or the message content. Filters may be applied at the email client, the ISP or a combination.

Email harvesting

An automated process in which a robot program searches web pages or other Internet destinations for email addresses. The program collects the address into a database, which frequently gets resold to spammers or unethical bulk mailers. Many U.S. state laws forbid harvesting. CAN-SPAM does not outlaw it by name but allows triple damages against violators who compiled their mailing lists with harvested names.

Email newsletter

Content distributed to subscribers by email on a regular schedule. The content is seen as valued editorial in itself ather than primarily a commercial message with a sales offer.

Email Prefix

The portion of the email address to the left of the @ sign.

Event triggered email

Pre-programmed messages sent automatically based on an event such as a date or anniversary.

False positive

A legitimate message mistakenly rejected or filtered as spam, either by an ISP or a recipient’s anti-spam program. The more stringent an antispam program, the higher its false-positive rate.

Feedback loop (FBL)

Information provided by a variety of ISPs about which subscribers are making your email as spam, as well as overall insight into your reputation with that ISP.


See email filter.


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From name

Whatever appears in the email recipient’s inbox as your visible “from” name. Chosen by the sender. May be a personal name, a brand name, an email address, a blank space, or alpha-numeric gobbledegook. Note – this is not the actual “from” contained in the header (see below) and may be different than the email reply address. Easy to fake. Aka Email Friendly Name.

Full-service provider

An email vendor that also provides strategic consulting and creative support, in addition to sending messages.

Goodbye message

An email message sent automatically to a list member who unsubscribes, acknowledging the request. Always include an option to resubscribe in case the unsubscribe was requested accidentally.

Hard bounce

Message sent to an invalid, closed or nonexistent email account.


Routing and program data at the start of an email message, including the sender’s name and email address, originating email server IP address, recipient IP address, and any transfers in the process.

House list:

The list of email addresses an organization develops on its own. (Your own list.)


The process of cleaning a database to correct incorrect or outdated values.


Internet Message Access Protocol, a standard protocol for accessing email from a server.


A single view of one page by a single user, used in calculating advertising rates.

IP address

A unique number assigned to each device connected to the Internet. An IP address can be dynamic (changing each time an email message goes out or campaign goes out), or it can be static (unchanging). Static IP addresses are best for email marketing, because dynamic IP addresses often trigger spam filters.

Landing page

A web page viewed after the user clicks a link within an email. Also may be called a microsite, splash page, bounce page, or click page.


The email addresses to which you send your message. Can be either your house list or a third-party list that sends your message on your behalf.

List owner

The organization or individual who has gathered a list of email addresses. Ownership does not necessarily imply that the addresses were collected “with permission.”

List rental

The process in which a publisher or advertiser pays a list owner to send its messages to that list. This usually involves the list owner sending the messages on the advertiser’s behalf.

List sale

The actual purchase of a mailing list along with the rights to mail it directly. Permission can only be “sold” if the subsequent mailings continue to match the frequency, brand name, content, and “from” of the past owner’s mailings — and even then this is a somewhat shaky procedure on the spam-front. You are in effect buying a publication, not just a list.


A code to make an email address in either a text or HTML email immediately clickable ( When the link is clicked, it usually opens the user’s email client and inserts the email address in the To field of a blank message.


Mail Transfer Agent. A computer that forwards email from senders to recipients (or to relay sites) and stores incoming email.


Also known (confusingly) as an “email sniffer.” This is a message format which includes both an HTML and a text-only version in the same message. Most (but not all) email clients receiving messages in this format will automatically display the version the user’s system is set to show. Systems that can’t show HTML should show the text version instead. This doesn’t always work — in particular for many Lotus Notes users.

Nth name

The act of segmenting a list for a test in which names are pulled from the main list for the test cell by number — such as every 5th name on the list. See also a/b split.

Open rate

The number of HTML message recipients who opened your email, usually as a percentage of the total number of emails sent. The open rate is considered a key metric for judging an email campaign’s success, but it has several problems. The rate indicates only the number of emails opened from the total amount sent, not just those that were actually delivered. Opens also can’t be calculated on text emails. Also, some email clients also use it to scan message content without actually opening the message, which is falsely calculated as an open. See preview pane.

Open relay

An SMTP email server that allows outsiders to relay email messages that are neither for nor from local users. Often exploited by spammers and hackers.


A specific pro-active request by an individual email recipient to have their own email address placed on a specific mailing list. Many list renters and buyers now require list owners to provide proof of opt-in, including the actual email or IP address date and time the request was received.


A specific request to remove an email address from a specific list, or from all lists operated by a single owner. Also, the practice of adding an email addresses to lists without the addressee’s pre-approval, forcing those who don’t want to be on your list to actively unsubscribe.


An email recipient who got your message via forwarding from a subscriber. (Some emails offer “forward to a friend” in the creative, but the vast majority of pass-alongs happen using email clients, and not that tech.) Pass-alongs can affect the formatting of the email, often stripping off HTML.


The implicit approval given when a person actively requests to have their own email address added to a list.


A targeting method in which an email message appears to have been created only for a single recipient. Personalization techniques include adding the recipient’s name in the subject line or message body, or having the message offer reflect a purchasing, link clicking, or transaction history.

PGP (Pretty Good Privacy)

Software used to encrypt and protect email as it moves from one computer to another and can be used to verify a sender’s identity.

Plain text

Text in an email message that includes no formatting code. See HTML.


Post Office Protocol, which an email client uses to exchange messages with n email server.


Whom to contact at a website, ISP or other site to request information, get help with delivery or register complaints.


Options a user can set to determine how they want to receive your messages, how they want to be addresses, to which email address message should go and which messages they want to receive from you. The more preferences a user can specify, the more likely you’ll send relevant email.

Preview pane

The window in an email client that allows the user to scan message content without actually clicking on the message. See open rate.


Where an email message goes after you send it but before the list owner approves it or before the list server gets around to sending it. Some list software allows you to queue a message and then set a time to send it automatically, either during a quiet period on the server or at a time when human approval isn’t available.

Read email

Not measurable. Only opens and clicks are measureable in any way. You can never know if a recipient simply read your message.

Relationship email

An email message that refers to a commercial action — a purchase, complaint or customer-support request — based on a business relationship between the sender and recipient. Generally are not covered by CAN-SPAM requirements.

Reverse DNS

The process in which an IP address is matched correctly to a domain name, instead of a domain name being matched to an IP address. Reverse DNS is a popular method for catching spammers who use invalid IP addresses. If a spam filter or program can’t match the IP address to the domain name, it can reject the email.

Rich Media

Creative that includes video, animation, and/or sound. Rich-media emails often collect high open and click rates but requires more bandwidth and are less compatible with different email clients than text or regular HTML email-format messages. Some mailers also consider transactional email “rich”.

Seed list

Email addresses placed on a list (sometimes secretly) to determine what messages are sent to the list and/or to track delivery rate and/or visible appearance of delivered messages. Seeds may also be placed on websites and elsewhere on the Internet to track spammers’ harvesting activities.


The ability to slice a list into specific pieces determined by various attributes, such as open history or name source.


A segment of a list determined by any number of attributes, such as source of name, job title, purchasing history, etc. CPM list renters pay an additional fee per thousand names for each select on top of the base list price.

Selective Unsubscribe

An unsubscribe mechanism that allows a consumer to selectively determine which email newsletters they wish to continue receiving while stopping the sending of others.

Sent emails

The number of email names transmitted in a single broadcast. This does not reflect how many were delivered or viewed by recipients.


Simple Mail Transfer Protocol, the most common protocol for sending email messages between email servers.

Soft bounce

Email sent to an active (live) email address but which is turned away before being delivered. Often, the problem is temporary — the server is down or the recipient’s mailbox is over quota. The email might be held at the recipient’s server and delivered later, or the sender’s email program may attempt to deliver it again. Soft-bounce reports are not always accurate because they don’t report all soft bounces or the actual reason for the bounce.


The popular name for unsolicited commercial email. However, some email recipients define spam as any email they no longer want to receive, even if it comes from a mailing list they joined voluntarily.


The practice of changing the sender’s name in an email message so that it looks as if it came from another address.

Subject line

Copy that identifies what an email message is about, often designed to entice the recipient into opening the message. The subject line appears first in the recipient’s inbox, often next to the sender’s name or email address. It is repeated in the email message’s header information inside the message.


To join a mailing list, either through an email command, by filling out a Web form, or offline by filling out a form or requesting to be added verbally. (If you accept verbal subscriptions, you should safeguard yourself by recording it and storing recordings along with time and date, in a retrievable format.)


The person who has specifically requested to join a mailing list. A list has both subscribers, who receive the message from the sender, and pass-alongs.

Suppression file

A Do Not Email list that you run against any lists you plan on sending mail to prior to the send. Required by CAN-SPAM.

Thank-you page

Web page that appears after user has submitted an order or a form online. May be a receipt.


The practice of regulating how many email messages a broadcaster sends to one ISP or mail server at a time. Seom ISP’s bounce mail if they receive too many messages from one sending address at a time.

Transactional email

Also known as transactive email. A creative format where the recipient can enter a transaction in the body of the email itself without clicking to a web page first. Transactions may be answering a survey, or purchasing something.


Unsolicited Commercial Email, also called spam or junk mail.


To remove oneself from an email list, either via an emailed command to the list server or by filling in a web form.

Video e-mail

An email message that includes a video file, either inserted into the message body, accessible through a hotlink to a Web site or accompanying it in an attachment (least desirable because many ISPs block executable attachments to avoid viruses).

Welcome message

A message sent automatically to new list members as soon as their email addresses are added successfully.


A list of email addresses authorized in advance, held by an ISP, subscriber or other email service provider, which allows email messages to be delivered regardless of spam filters.


A piece of malicious code, often delivered via an executable attachment in email or over a computer network.