Email marketing glossary 60 terms in plain English

Email marketing has its own vocabulary, and several of its words hide a trap. "Delivered" does not mean the inbox. An "open" can be Apple's servers fetching images for a phone that never showed the email. This email marketing glossary defines the 60 terms you are most likely to meet in platform dashboards, monthly reports and agency proposals, each in one or two plain sentences, grouped from A to Z.

Where Google, Yahoo, Apple or the FTC has published a rule, the definition gives the number and names the source. The rest are working definitions from the campaigns we plan and write. Nothing here is legal advice.

Which email marketing terms should you learn first?

You do not need every term on day one. Start with the group that matches the job in front of you.

Email marketing glossary: terms from A to Z

Acronyms sit under their first letter, so DKIM is filed under D and CTA under C. Common synonyms, such as CTR for click rate, appear in parentheses after the main term.

A

A/B test

Sending two versions of one email to random slices of a list, then sending the better performer to everyone else. Change one thing at a time, such as the subject line or the offer, or you will never know what made the difference.

Abandoned cart email

An automated email sent after a shopper adds items to a cart and leaves without buying, with a link straight back to that cart. It is a flow, not a campaign, because the shopper's action triggers it rather than a date you pick.

Activation campaign

An email that moves people who signed up, but have not used the product yet, toward their first meaningful action. It matters most for SaaS and apps, where an unused signup is worth little.

Alt text

The description attached to an image, shown when images are blocked and read aloud by screen readers. Write the message the image carries, such as "Up to 25% off consoles", not a file name.

B

BIMI (Brand Indicators for Message Identification)

A standard that lets supporting inboxes show your logo beside your messages. Google requires a DMARC policy of quarantine or reject at pct=100 plus a third party certificate, and Gmail adds a checkmark for senders verified with a Verified Mark Certificate.

Blocklist

A list of IP addresses or domains flagged for sending spam, which mailbox providers consult when filtering. Older guides call it a blacklist, and landing on a major one can sharply cut delivery until you are removed.

Bounce rate

Bounced emails divided by sent emails, where a bounce is a message the receiving server refused. Bounces come in two kinds, hard and soft, and a rising rate usually points to old addresses or a signup form that lets typos through.

Bulk sender

Google's label for anyone who sends close to 5,000 or more messages to personal Gmail accounts within 24 hours. Google says the label is permanent once earned, and it brings stricter rules, including DMARC and one click unsubscribe.

C

Call to action (CTA)

The single next step you want a reader to take, usually a button such as "Book your site". One clear CTA beats five competing ones.

Campaign

One planned email sent to a list or segment at a time you choose, such as a sale announcement or a newsletter. Campaigns are what we deliver: 8 finished campaigns a month for one flat fee.

CAN-SPAM Act

The US federal law for commercial email. The FTC's compliance guide requires truthful headers and subject lines, your valid physical postal address, a clear way to opt out and opt outs honored within 10 business days, and each violating email can draw a penalty of up to $53,088.

Click rate (click through rate, CTR)

Unique clickers divided by delivered emails. Now that opens are inflated, it is the most dependable engagement number in most reports.

Click to open rate (CTOR)

Unique clickers divided by unique openers. It shows how well the body persuaded the people who opened, but inflated opens drag it down, so read it as a trend rather than a verdict.

Complaint rate (spam rate)

The share of delivered emails that recipients mark as spam. Google tells senders to stay below 0.10% in Postmaster Tools and never reach 0.30%, and Yahoo tells bulk senders to keep it below 0.3%. Mailbox providers pass these reports back through feedback loops (FBLs), and Yahoo says an active Complaint Feedback Loop is needed for every DKIM domain.

Conversion rate

The share of people who complete the goal, such as a purchase or a booking. Always say whether you divided by delivered emails or by clicks, because the two give very different numbers.

Cross sell

Offering a product that pairs with the one the reader is already considering, such as a mirror to hang above a console table.

D

Dark mode

A setting that shows light text on a dark background, and some email apps also invert an email's colors to match. Logos and text need to stay readable when the colors flip.

Dedicated IP

A sending IP address used by your account alone. It only pays off with large, steady volume, so most small businesses are better served by their platform's shared IPs.

Deliverability

Your ability to reach the inbox rather than the spam folder or a rejection. It rests on authentication (the SPF, DKIM and DMARC records that Gmail and Yahoo require from bulk senders), sender reputation, list quality and whether people actually want your mail.

Delivery rate

Delivered emails divided by sent emails. Delivered only means a server accepted the message, so a 99% delivery rate can still hide a spam folder problem.

DKIM (DomainKeys Identified Mail)

A cryptographic signature added to every message and checked against a public key published in your DNS. Defined in RFC 6376, it lets your domain claim responsibility for a message and shows the signed content has not changed since it was signed.

DMARC (Domain based Message Authentication, Reporting and Conformance)

A DNS record that tells receivers what to do with mail that fails authentication (none, quarantine or reject) and where to send reports. Google and Yahoo require bulk senders to publish one, with p=none as the minimum.

DMARC alignment

The match between the domain in your visible From address and the domain that passed SPF or DKIM. Google and Yahoo require bulk mail to align with at least one of them, so mail authenticated only by your platform's shared domain does not count.

Double opt in

A signup that only becomes active after the person clicks a link in a confirmation email. Single opt in skips that step, which grows a list faster but lets typos and fake addresses in.

Drip campaign (autoresponder)

A set of emails sent automatically at fixed intervals after a starting event, such as day 1, day 3 and day 7 of a free trial. Despite the name, it runs as a flow rather than as a dated campaign.

E

Email service provider (ESP)

The platform that stores your contacts and sends your campaigns, such as Klaviyo, Mailchimp, HubSpot or Brevo. Not to be confused with a mailbox provider, which receives mail.

F

Flow

Klaviyo's word for an automated sequence that starts on a trigger, such as joining a list or placing an order. Other platforms call the same idea an automation, a journey or a workflow.

From name

The sender name shown in the inbox next to the subject line. Readers check it first, so keep it consistent from send to send.

G

Gmail clipping

Gmail cuts off long messages and shows a "View entire message" link. Litmus says Gmail clips any message whose code tops 102 KB, images not included, and everything past the cut stays hidden until the reader taps that link.

Google Postmaster Tools

Google's dashboard showing how Gmail sees mail from your domain to personal Gmail addresses, including spam rate, message authentication and delivery errors. It is where Google measures the 0.10% and 0.30% spam rate thresholds.

H

Hard bounce

A permanent failure, usually because the address does not exist or the domain is gone. Stop mailing a hard bounced address after the first failure; most platforms suppress it automatically.

I

Inbox placement

The share of delivered mail that lands in the inbox rather than spam. No platform reports it exactly, so senders estimate it with seed tests, which send a campaign to a panel of test inboxes, and Postmaster Tools data.

IP warming

Raising send volume gradually on a new IP address or domain so mailbox providers can learn to trust it. Mailing a full list from a cold IP on day one invites the spam folder.

L

List hygiene

Regular cleanup of your email list: removing bounces, fixing typo domains like gmial.com and suppressing people who have not engaged in months.

List unsubscribe header

A hidden header that lets inboxes such as Gmail and Yahoo show their own unsubscribe button. RFC 8058 defines the one click version, which Google and Yahoo now require on bulk marketing mail.

M

Mailbox provider

The company hosting the recipient's inbox, such as Gmail, Yahoo or Outlook.com. Its filters, not your platform, decide whether a message reaches the inbox.

Mail Privacy Protection (MPP)

An Apple Mail feature that hides the reader's IP address and, according to Apple, downloads remote content in the background whether or not the reader engages with the email. That makes opens from Apple Mail users unreliable.

N

Newsletter

A recurring email, such as a weekly or monthly roundup, that mixes news, useful content and an offer and goes to your whole list or a broad segment. It is a campaign, not a flow, and our newsletter management service covers the content mix, cadence and writing.

O

Open rate

Unique opens divided by delivered emails. An open is logged when a tiny invisible image called a tracking pixel loads, so image blocking and Mail Privacy Protection both distort it. It now overstates real reading, so compare it only against your own past sends.

Opt in

Permission to email someone, given through a signup form, a checkout box or a similar clear action. Mailchimp, for one, bans sending to purchased, rented or third party lists in its Acceptable Use Policy.

Opt out

A request to stop receiving your commercial email. CAN-SPAM allows 10 business days to honor it, but Yahoo asks for 2 days and Google recommends 48 hours, so 2 days is the practical deadline.

P

Personalization

Using data you hold to tailor an email to each reader. The simplest form is a merge tag, a placeholder such as a first name that your platform fills in at send time, so always set a fallback or someone gets "Hi ,". Dynamic content goes further and swaps whole blocks, such as showing different products to past buyers and to new subscribers.

Preference center

A page linked from your emails where subscribers choose the topics they want and how often, instead of leaving altogether. The FTC allows a menu like this under CAN-SPAM as long as one choice stops all marketing messages from you.

Preheader

The line of text that follows the subject line in most inbox views, also called preview text. Leave it empty and the inbox grabs the first words of the email, which are often "View in browser".

R

Responsive email design

A layout that adapts to the screen, usually by stacking columns into one on phones and making buttons easy to tap. It depends on live text, real words in the code rather than words baked into an image, which also show with images off and read correctly in screen readers. Our email design service builds every email this way.

Revenue per recipient (RPR)

Revenue credited to a campaign divided by the number of people it was delivered to. It lets you compare a small, targeted send with a big blast fairly.

S

Segment

A group of contacts defined by rules, such as "bought in the last 90 days" or "lives in Texas". In Klaviyo, segments update as people meet or stop meeting the rules, while a list grows only when people subscribe or are added.

Sender reputation

The trust mailbox providers place in your sending domain and IP, built from complaints, bounces, spam trap hits and engagement. You never see one official score, but Postmaster Tools shows some of the signals behind it.

Soft bounce

A temporary failure, such as a full mailbox or a server that is briefly down. Platforms retry, and an address that keeps soft bouncing is usually treated as a hard bounce.

Spam trap

An address that mailbox providers or blocklist operators use to catch senders with poor list practices, either one no person ever used or an abandoned address put back to work. Mailing either kind hurts your reputation.

SPF (Sender Policy Framework)

A DNS record listing the servers allowed to send mail for your domain. RFC 7208 caps an SPF check at 10 DNS lookups, and a record that needs more produces a permanent error.

Subject line

The headline of your email in the inbox and the main reason it gets opened or ignored. It works as a pair with the preheader, and our subject line guide has formulas and examples.

Sunset policy

A rule that stops mailing contacts after a set stretch without opens or clicks, usually after one last win back email. It keeps complaints down and your numbers honest.

Suppression list

Addresses your platform will never mail, such as unsubscribes, hard bounces and spam complainers. Export it when you switch platforms, or you risk emailing people who already opted out.

T

Transactional email

A message that completes something the reader started, such as a receipt, shipping notice or password reset. The FTC sorts messages by primary purpose: if the main purpose is to promote a product or service, commercial rules apply even when the email also carries account details. True transactional and relationship messages are exempt from most CAN-SPAM rules, but they still cannot contain false or misleading routing information.

U

Unsubscribe rate

Unsubscribes divided by delivered emails. A spike after one send tells you that campaign missed on topic, timing or frequency.

UTM parameters

Tags added to links, such as utm_source and utm_campaign, that tell your analytics tool which email sent a visitor. Without them, email traffic often gets lumped in with direct visits.

W

Welcome series

The automated emails a new subscriber receives after joining. It runs as a flow, not a campaign, so we quote it separately from the monthly plan.

Win back campaign

An email aimed at subscribers or customers who have gone quiet, giving them a reason to come back before a sunset policy removes them.

Z

Zero party data

Information a subscriber tells you on purpose, such as preferences chosen in a quiz or a signup form. It is the most reliable data for personalization because nobody had to guess it.

Which email marketing terms get confused most often?

Many reporting arguments come down to two people using one word for two different things. These are the pairs that cause the most trouble.

What do Mailchimp, Klaviyo and HubSpot call the same features?

Every platform also has its own labels. Mailchimp calls your full contact database an audience and organizes it with tags, groups and segments. Klaviyo separates static lists from dynamic segments and calls its automations flows, as its guide to segments explains. HubSpot divides contacts into marketing and non marketing contacts, and only marketing contacts count toward the billable contact tier. We work inside these and several more, and our page on the email platforms we support covers who each one suits.

What do these terms look like in real campaigns?

Here are campaigns we designed and wrote, each matched to one term. We do not publish client performance numbers, so these describe the idea, not the results.

You can see the full set, including the other RV park emails, on our email marketing examples page.

Would you rather not learn all of this?

That is a fair choice. At EmailMarketingAgency.com we handle the campaign work behind these terms for $1,000 a month, flat, for 8 finished campaigns: strategy, copy, design, segmentation, subject line A/B tests, QA, scheduling and deliverability monitoring, plus one plain English report a month in the same words used here. To see where your list stands first, ask for a free email marketing audit.

Frequently asked questions