The Ultimate Email Glossary: 178 Common Terms Defined

Below are email terms you're most likely to come across as you deal with the email process, building your list, creating and sending messages, or dealing with your IT department or broadcast vendor.

Note: See something missing? Email us at feedback@marketingsherpa.com

A/B split: Refers to a test situation in which a list is split into two pieces with every other name being sent one specific creative, and vice versa. See also Nth name.

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, etc.

Access: Microsoft software tool used for developing a database. Any database vendor you work with -- email broadcaster, list broker, third-party list-hygiene service, etc. -- should be able to work with this format (as well as several others.)

Acquisition cost: In email marketing, the cost to generate one lead, newsletter subscriber or customer in an individual email campaign; typically, the total campaign expense divided by the number of leads, subscribers or customers it produced.

Ad swap: An exchange between two publishers in which each agrees to run the other's comparably valued ad at no charge. Value is determined by rate card, placement, size of list, quality of list, name brand fame, etc.

Affiliate: A marketing partner that promotes your products or services under a payment-on-results agreement.

Affirmative consent: An active request by a reader or subscriber to receive advertising or promotional information, newsletters, etc. Generally affirmative consent does not included the following -- failing to uncheck a pre-checked 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, opt-out.

Alert: Email message that notifies subscribers of an event or special price.

AOL: America Online.

Application Program Interface (API): How a program (application) accesses another to transmit data. A client may have an API connection to load database information to an email vendor automatically and receive data back from the email.

Application Service Provider (ASP): Company that provides a Web-based service. Clients don’t have to install software on their own computers; all tasks are performed on (hosted on) the ASP’s servers.

Attachment: A text, video, graphic, PDF or sound file that accompanies an email message but is not included in the message itself. Attachments are not a good way to send email newsletters because many ISPs, email clients and individual email recipients do not allow attachments, because hackers use them to deliver viruses and other malicious code.

Authentication: An automated process that verifies an email sender's identity.

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

Bayesian filter: An anti-spam program that evaluates header and content of incoming email messages to determine the probability that it is spam. Bayesian filters assign point values to items that appear frequently in spam, such as the words "money-back guarantee" or "free." A message that accumulated too many points is either rejected as probable spam or delivered to a junk-mail folder. Aka content-based filter.

B-to-B: Business-to-business (also B2B).

B-to-C: Business-to-consumer (also B2C).

Blacklist: 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. Also Blocklist and Blackhole list.

Block: A refusal by an ISP or mail server not to forward your email message to the recipient. Many ISPs block email from IP addresses or domains that have been reported to send spam or viruses or have content that violates email policy or spam filters.

Bonded Sender: A private email-registration service, owned by email vendor Ironport, which allows bulk emailers who agree to follow stringent email practices and to post a monetary bond to bypass email filters of Bonded Sender clients. The programs debits the bond for spam or other complaints from recipients.

Bounce: A message that doesn’t get delivered promptly is said to have bounced. Emails can bounce for more than 30 reasons: 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 message: Message sent back to an email sender reporting the message could not be delivered and why. Note: Not all bounced emails result in messages being sent back to the sender. Not all bounce messages are clear or accurate about the reason email was bounced.

Bounce handling: The process of dealing with the email that has bounced. Bounce handling is important for list maintenance, list integrity and delivery. Given the lack of consistency in bounce messaging formats, it's an inexact science at best.

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.

Broadcast: The process of sending the same email message to multiple recipients.

Bulk folder (also junk folder): Where many email clients send messages that appear to be from spammers or contain spam or are from any sender who’s not in the recipient’s address book or contact list. Some clients allow the recipient to override the system’s settings and direct that mail from a suspect sender be sent directly to the inbox. E.g., Yahoo!Mail gives recipients a button marked “Not Spam” on every message in the bulk folder.

Call to action: In an email message, the link or body copy that tellst the recipient what action to take.

CAN-SPAM: Popular name for the U.S. law regulating commercial email (Full name: Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003)

Catch-all: 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.

Cell: Aka Test cell or version. A segment of your list that receives different treatment specifically to see how it responds versus the control (regular treatment.)

CGI: Acronym for Common Gateway Interface. It is a specification for transferring information between the Web and a Web server, such as processing email subscription or contact forms.

Challenge-response system: An anti-spam program that requires a human being on the sender's end to respond to an emailed challenge message before their messages can be delivered to recipients. Senders who answer the challenge successfully are added to an authorization list. Bulk emailers can work with challenge-response if they designate an employee to watch the sending address' mailbox and to reply to each challenge by hand. Churn: How many subscribers leave a mailing list (or how many email addresses go bad) over a certain length of time, usually expressed as a percentage of the whole list.

clickthrough & clickthrough tracking: When a hotlink is included in an email, a clickthrough occurs when a recipient clicks on the link. clickthrough tracking refers to the data collected about each clickthrough link, such as how many people clicked it, how many clicks resulted in desired actions such as sales, forwards or subscriptions.

clickthrough rate: Total number of clicks on email link(s) divided by the number of emails sent. Includes multiple clicks by a unique user. Some email broadcast vendors or tracking programs define CTR differently.

Commercial email: Email whose purpose, as a whole or in part, is to sell or advertise a product or service or if its purpose is to persuade users to perform an act, such as to purchase a product or click to a Web site whose contents are designed to sell, advertise or promote.

Confirmation: An acknowledgment of a subscription or information request. "Confirmation" can be either a company statement that the email address was successfully placed on a list, or a subscriber's agreement that the subscribe request was genuine and not faked or automatically generated by a third party.

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. Ask anyone using this term to define it more clearly.

Content: All the material in an email message except for the codes showing the delivery route and return-path information. Includes all words, images and links.

Co-registration: 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.

Conversion: When an email recipient performs a desired action based on a mailing you have sent. A conversion could be a monetary transaction, such as a purchase made after clicking a link. It could also include a voluntary act such as registering at a Web site, downloading a white paper, signing up for a Web seminar or opting in to an email newsletter.

CPA: Cost per Action (also can be Acquisition). A method of paying for advertising, or calculating results from non-CPA marketing.

CPC: Cost per Click. A method of paying for advertising. 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.

CPM: Cost per Thousand.

Creative: An email message's copy and any graphics.

CRM: Customer Relationship Management technology and systems

Cross-campaign profiling: A method used to understand how email respondents behave over multiple campaigns.

Cross-post: To send the same email message to at least two different mailing lists or discussion groups.

CTR: Clickthrough Rate. Slightly inexact because some clicks "get lost" between the click and your server. Also be sure to ask if the CTR is unique, meaning that each individual user is only counted once no matter how many times they click on a link.

Dedicated Server: An email server used by only one sender. A dedicated server often costs more to use because the expense can't be spread among many users, but it performs better than a shared server. Email usually goes out faster, the server is more secure, and you eliminate the possibility that another sender could get the server blacklisted for spamming.

Deduplication (deduping): The process of removing identical entries from two or more data sets such as mailing lists. AKA merge/purge. Delivered email: Number of emails sent minus the number of bounces and filtered messages. A highly inexact number because not all receiving ISPs report accurately on which email 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.

Denial-of-service attack (DOS): An organized effort to disrupt email or Web service by sending more messages or traffic than a server can handle, shutting it down until the messages stop.

Deploy:The act of sending the email campaign after testing.

Digest: A shortened version of an email newsletter which replaces full-length articles with clickable links to the full article at a Web site, often with a brief summary of the contents.

Discussion group: An email service in which individual members post messages for all group members to read ("many to many.") In contrast, a newsletter is a "one to many" broadcast, where comments by members or subscribers go only to the message sender. Aka by the trademarked name Listserv.

DomainKeys: 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.

Domain Name System: How computer networks locate Internet domain names and translate them into IP addresses. The domain name is the actual name for an IP address or range of IP addresses. E.g. MarketingSherpa.com. See reverse DNS.

Double opt-in: A process that requires new list joiners to take an action (such as clicking on an emailed link to a personal confirmation page) in order to confirm that they do want to be on the list. Sometimes interpreted incorrectly by some email broadcast vendors to mean a new subscriber who does not opt-out of or bounce a welcome message.

Dynamic content: Email-newsletter content that changes from one recipient to the next according to a set of predetermined rules or variables, usually according to preferences the user sets when opting in to messages from a sender. Dynamic content can reflect past purchases, current interests or where the recipient lives.

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

Effective rate: Metric that measures how many of those who opened an email message clicked on a link, usually measured as unique responders divided by unique opens.

Email address: The combination of a unique user name and a sender domain (JohnDoe@anywhere.com). The email address requires both the user name and the domain name.

Email appending: Service that matches email addresses to a database of personal names and postal addresses. Appending may require an "OK to add my name" reply from the subscriber before you can add the name to the list.

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

Email Domain: Aka Domain. The portion of the email address to the right of the @ sign. Useful as an email address hygiene tool (e.g. identify all records where the consumer entered "name@aol" as their email address and correct it to "name@aol.com").

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

Email Friendly Name Aka Display Name, From name. The portion of the email address that is displayed in most, though not all, email readers in place of, or in addition to, the email address.

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. Content is seen as valued editorial in and of itself rather than primarily a commercial message with a sales offer. See ezine.

Email Prefix: The portion of the email address to the left of the @ sign.

Email vendor: Another name for an email broadcast service provider, a company that sends bulk (volume) email on behalf of their clients. Also email service provider (ESP).

Enhanced whitelist: A super-whitelist maintained by AOL for bulk emailers who meet strict delivery standards, including fewer than 1 spam complaint for every 1,000 email messages. Emailers on the enhanced whitelist can bypass AOL 9.0’s automatic suppression of images and links.

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

Ezine (also e-zine): Another name for email newsletter, adapted from electronic ‘zine or electronic magazine.

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 anti-spam program, the higher the false-positive rate. FAQ: Frequently Asked Questions.

Filter: See email filter.

Firewall: A program or set of programs designed to keep unauthorized users or messages from accessing a private network. The firewall usually has rules or protocols that authorize or prohibit outside users or messages. In email, a firewall can be designed so thast messages from domains or users listed as suspect because of spamming, hacking or forging will not be delivered.

Footer:An area at the end of an email message or newsletter that contains information that doesn’t change from one edition to the next, such as contact information,the company’s postal address or the email address the recipient used to subscribe to mailings. Some software programs can be set to place this information automatically.

Forward (also Forward to a Friend): The process in which email recipients send your message to people they know, either because they think their friends will be interested in your message or because you offer incentives to forward messages. Forwarding can be done through the recipient’s own email client or by giving the recipient a link to click, which brings up a registration page at your site, in which you ask the forwarded to give his/her name and email address, the name/email address of the person they want to send to and (optionally) a brief email message explaining the reason for the forward.You can supply the wording or allow the forward to write his/her own message. AKA viral marketing.

From: 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.

Gmail: A new, free email service offered by Google, giving users 1GB of storage space, email search and conversation threading. Gmail also uses technology to add advertisements next to messages containing keywords that match of those advertisers in its AdWords program, a policy that means promotional materials sent by one company could carry text ads of its competitors.

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.

HTML message: Email message which contains any type of formatting other than text. This may be as simple as programming that sets the text in a specific font (bold, italics, Courier 10 point, etc.). It also includes any graphic images, logos and colors.

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

Header: 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.)

Hygiene: The process of cleaning a database to correct incorrect or outdated values. See also List Hygiene.

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

Impression: 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, meaning it changes each time an email message or campaign goes out, or it can be static, meaning it does not change. Static IP addresses are best, because dynamic IP addresses often trigger spam filters.

ISP: Internet Service Provider. Examples: AOL, EarthLink, MSN

Joe job: A spam-industry term for a forged email, in which a spammer or hacker fakes a genuine email address in order to hide his identity.

Landing page: A Web page viewed after clicking on a link within an email. Also may be called a microsite, splash page, bounce page, or click page.

Linkrot: What happens when links go bad over time, either because a Web site has shut down or a site has stopped supporting a unique landing page provided in an email promotion.

List: The list of 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 fatigue: A condition producing diminishing returns from a mailing list whose members are sent too many offers, or too many of the same offers, in too short a period of time.

List host: See email vendors.

List hygiene: The act of maintaining a list so that hard bounces and unsubscribed names are removed from mailings. Some list owners also use an email change-of-address service to update old or abandoned email addresses (hopefully with a permission step baked in) as part of this process.

List management: How a mailing list is set up, administered and maintained. The list manager has daily responsibility over list operation, including processing subscribes and unsubscribes, bounce management, list hygiene, etc. The list manager can be the same as the database manager but is not always the same person as the list owner. See list owner.

List owner: The organization or individual who has gathered a list of email addresses. Ownership does not necessarily imply "with permission."

List rental: The process in which a publisher or advertiser pays a list owner to send its messages to that list. Usually involves the list owner sending the message's on the advertiser's behalf. (If someone hands over their list to you, beware.)

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, and not just a list.

Mail bomb: An orchestrated attempt to shut down a mail server by sending more messages than it can handle in a short period of time. See DOS.

Mailing list: A list of email addresses that receive mailings or discussion-group messages.

Mail loop: A communication error between two email servers, usually happening when a misconfigured email triggers an automated response from the recipient server.

mailto: : A code to make an email address in either a text or HTML email immediately clickable (mailto:JohnDoe@anywhere.com). When the link is clicked, it usually opens the user's email client and inserts the email address in the To: link of a blank message.

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

MSP: Mail service provider, such as Hotmail.

MUA: Mail User Agent (see email client).

Multi-part MIME: Also known (confusingly) as an "email sniffer." 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. Also, no data, except HTML open rates and possibly link click tracking, is transmitted back to the sender regarding which version a recipient wound up viewing.

MX: Mail Exchange Record

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 users 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.

Opt-in: 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.

Opt-out: A specific request to remove an email address from a specific list, or from all lists operated by a single owner. Also, the process of adding an email addresses to lists without the name's pre-approval, forcing names who don't want to be on your list to actively unsubscribe.

Pass-along: 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. Also known as viral.

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

Personalization: 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 the message offer reflects 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.

Phishing: A form of identity theft in which a scammer uses an authentic-looking email to trick recipients into giving out sensitive personal information, such as credit-card or bank account numbers, Social Security numbers and other data.

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

POP: Post Office Protocol, which an email client uses to send to or receive messages from an email server.

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

Preferences: 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.

Privacy policy: A clear description of how your company uses the email addresses and other information it gathers via opt-in requests for newsletters, company information or third-party offers or other functions. If you rent, sell or exchange your list to anyone outside your company, or if you add email addresses to opt-out messages, you should state so in the privacy policy. State laws may also compel you to explain your privacy policy, where to put the policy statement so people will see it and even in form the policy should be displayed.

Queue: 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.

Registration: The process where someone not only opts in to your email program but provides some additional information, such as name, address, demographic data or other relevant information, usually by using a Web form.

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.

Reply-to: The email address that receives messages sent from users who click “reply” in their email clients. Can differ from the “from”address which can be an automated or unmonitored email address used only to send messages to a distribution list. “Reply-to” should always be a monitored address.

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 emails: 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 Web sites and elsewhere on the Internet to track spammers' harvesting activities.

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

Select: 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.

Sender ID: The informal name for a new anti-spam program combining two existing protocols: Sender Policy Framework and CallerID. SenderID authenticates email senders and blocks email forgeries and faked addresses.

Sender Policy Framework (also SPF): A protocol used to eliminate email forgeries. A line of code called an SPF record is placed in a sender’s Domain Name Server information. The incoming mail server can verify a sender by reading the SPF record before allowing a message through.

Sent emails: Number of email names transmitted in a single broadcast. Does not reflect how many were delivered or viewed by recipients.

Server: A program or computer system that stores and distributes email from one mailbox to another, or relays email from one server to another in a network.

Shared server: An email server used by more than one company or sender. Shared servers are less expensive to use because the broadcast vendor can spread the cost over more users. However, senders sharing a server risk having emails blocked by major ISPs if one of the other users does something to get the server's IP address blacklisted. See dedicated server.

Signature: A line or two of information found in the closing of an email, usually followed the sender’s name. Signatures can include advertising information, such as a company name, product, brand message or marketing call to action (subscribe to a company newsletter with the email subscribe address or Web registration form, or visit a Web site with the URL listed).

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

Snail mail: postal mail.

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.

Solo mailing: A one-time broadcast to an email list, separate from regular newsletters or promotions, and often including a message from an outside advertiser or a special promotion from the list owner.

Spam: 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.

Spamcop: A blacklist and IP-address database, formerly privately owned but now part of the email vendor Ironport. Many ISPs check the IP addresses of incoming email against Spamcop’s records to determine whether the address has been blacklisted due to spam complaints.

Sponsorship swap: An agreement between email list owners, publishers or advertisers to sponsor each other's mailings or newsletters for free. See ad swap.

Spoofing: 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.

Subscribe: The process of joining 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.)

Subscriber: 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 list of email addresses you have removed from your regular mailing lists, either because they have opted out of your lists or because they have notified other mailers that they do not want to receive mailings from your company. Required by CAN-SPAM. AKA Do-Not-Email list.

Test: A necessary step before sending an email campaign or newsletter. Many email clients permit you to send a test email before sending a regular email newsletter or solo mailing, in which you would send one copy of the message to an in-house email address and then review it for formatting or copy errors or improperly formatted links. Email marketers should also send a test campaign to a list of email addresses not in the deployment database to determine likely response rates and how well different elements in the message perform.

Text newsletter: Plain newsletter with words only, no colors, graphics, fonts or pictures; can be received by anyone who has email.

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

Throttling: The practice of regulating how many email message a broadcaster sends to one ISP or mail server at a time. Some ISPs bounce email if it receives 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.

UCE: Unsolicited Commercial Email, also called spam or junk mail.

Unique Reference Number: A unique number assigned to a list member, usually by the email-broadcast software, and used to track member behavior (clicks, subscribes, unsubscribe) or to identify the member to track email delivery.

URL (Uniform Resource Locator): The Web address for a page, always beginning with http:// (or https:// for a secure page) and followed by www. (or variations, although some URLs are set up not to include this information) and the domain name. E.g., http://www.marketingsherpa.com .

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

Vendor: Any company that provides a service. See email vendors.

Verification: A program that determines an email came from the sender listed in the return path or Internet headers; designed to stop email from forged senders.

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).

Virus: A program or computer code that affects or interferes with a computer’s operating system and gets spread to other computers accidentally or on purpose through email messages, downloads, infected CDs or network messages. See worm.

Web bug (also Web beacon): A 1 pixel-by-1 pixel image tag added to an HTMLmessage and used to track open rates by email address. Opening the message, either in the preview pane or by clicking on it, activates the bug and sends a signal to the Web site, where special software tracks and records the signal as an open. Webmail (also Web mail): Any of several Web-based email clients where clients have to go to a Web site to access or download email instead of using a desktop application. Some examples are Gmail, Yahoo! Mail and Hotmail.

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

Whitelist: Advance-authorized list of email addresses, held by an ISP, subscriber or other email service provider, which allows email messages to be delivered regardless of spam filters. See also enhanced white list.

Worm: A piece of malicious code delivered via an executable attachment in email or over a computer network and which spreads to other computers by automatically sending itself to every email address on a recipient’s contact list or address book. See virus.