Email Marketing Glossary: Terms Every Sender Should Know

What this covers#

A short definition of each term you are likely to meet when you send email campaigns — in this knowledge base, in your sending provider's dashboard and in campaign reports. The terms are grouped by topic. Where a term has a full article, the definition links to it.

Audience and permission#

Term	What it means
List	A set of contacts you send to. Each contact has at least an email address; most lists also store a name and other details.
Contact (subscriber)	One person on a list.
Opt-in	A person agreeing to receive your email — for example by filling in a signup form.
Single opt-in	The address joins the list as soon as the form is submitted.
Double opt-in (confirmed opt-in)	After submitting the form, the person clicks a link in a confirmation email before the address joins the list. It proves the address exists and belongs to the person who signed up.
Consent	The permission a person gave you to email them. Several laws require you to be able to show when and how it was given.
Unsubscribe (opt-out)	A person's request to stop receiving your email. Every marketing email must offer a working way to do it.
Suppression list	Addresses you must not send to again — people who unsubscribed, complained or hard-bounced. It is kept even when the address is imported again later.
Segment	A part of a list chosen by rules, such as "clicked in the last 90 days" or "country is Germany".
Custom field	Extra information stored for each contact — company, plan, birthday — that you can segment on or insert into an email.
Role address	An address that belongs to a function rather than a person, such as info@ or sales@. No single person signed up, so consent is hard to show, and some sending providers restrict mail to these addresses.

Sending#

Term	What it means
ESP (email service provider)	A company or platform that sends email for you and gives you tools to manage lists and campaigns.
Sending server (sending service)	The system that actually transmits your messages: your own mail server, or a service such as Amazon SES, SendGrid or Mailgun.
SMTP	Simple Mail Transfer Protocol — the standard mail servers use to pass messages to each other.
MTA (mail transfer agent)	Mail server software that sends and receives email over SMTP, such as Postfix.
Mailbox provider	The company that hosts the recipient's inbox — Gmail, Outlook.com, Yahoo and so on.
Sending domain	The domain in your From address, for example news.example.com.
Envelope sender (Return-Path)	The address bounces go back to. It is set when the message is handed over and can differ from the From address the reader sees. See Return-Path vs Envelope-Sender.
MX record	A DNS record naming the servers that accept mail for a domain.
Dedicated IP	A sending IP address used only by you, so its reputation reflects only your mail. See Dedicated vs Shared Sending IP.
Shared IP	An IP address a sending provider uses for many senders at once.
Throttling	Limiting how fast you send, for example to a maximum number of messages per hour. See Email Throttling & Rate Limits.
Warmup	Raising volume gradually on a new IP address or domain, so mailbox providers can build a reputation for it. See Domain Warmup.

Authentication#

Term	What it means
SPF	Sender Policy Framework. A DNS record listing the servers allowed to send mail for your domain.
DKIM	DomainKeys Identified Mail. The sending server signs each message with a private key; the receiver checks the signature against the public key in your DNS. A valid signature shows the message was not changed on the way and was authorised by the signing domain.
DMARC	A DNS record that tells receivers what to do with mail that fails authentication for your domain — nothing (p=none), send it to spam (p=quarantine) or refuse it (p=reject) — and where to send reports.
Alignment	For DMARC, the domain that passed SPF or DKIM must match the domain in the From address the reader sees.
BIMI	A DNS record that lets supporting mailbox providers show your logo next to your mail. It needs a DMARC policy of quarantine or reject, and Gmail also requires a mark certificate. See BIMI Setup.

How to publish all three records: How to Set Up SPF, DKIM, and DMARC Records.

Delivery results#

Term	What it means
Delivered	The receiving server accepted the message. It says nothing about which folder the message landed in.
Bounce	A message the receiving server refused, reported back to the sender.
Hard bounce	A permanent failure, such as an address that does not exist. Stop sending to it.
Soft bounce	A temporary failure, such as a full mailbox or a server that is briefly unavailable. The message is retried; an address that keeps soft-bouncing is eventually treated like a hard bounce. See Hard Bounce vs Soft Bounce.
Complaint (spam report)	The recipient clicked "Report spam" (or the equivalent) in their mail app.
Feedback loop (FBL)	A service some mailbox providers run that reports complaints back to the sender, so the address can be suppressed. See Feedback Loops (FBL).
Inbox placement	Where a delivered message was filed — the inbox, a tab such as Promotions, or the spam folder.
Deliverability	Your overall ability to get mail into inboxes, not merely delivered.
Sender reputation	The trust mailbox providers place in your sending IP addresses and domains, built from how your mail has been received over time.
Spam trap	An address that no active person uses, kept to catch senders who mail addresses they should not have.
Blocklist	A list of IP addresses or domains known for sending spam, which many receiving servers check before accepting mail.

Messages#

Term	What it means
Campaign	One email sent to a list or segment at a time you choose, such as a newsletter or a promotion.
Automation (workflow)	Emails sent automatically when a contact does something or meets a condition, such as signing up or buying.
Transactional email	A message triggered by one person's action, such as a receipt or a password reset, rather than sent to a list.
Subject line	The line shown in the inbox before the message is opened.
Preheader	The short text most inboxes show next to or under the subject line. It is taken from the start of the email unless you set it.
Merge tag	A placeholder, such as the contact's first name, replaced with each contact's own data when the email is sent.
Call to action (CTA)	The link or button asking the reader to do the one thing the email is for.
A/B test (split test)	Sending two versions of an email to parts of a list to see which works better, then sending the winner to the rest.
List-Unsubscribe header	A hidden header that lets mail apps show their own unsubscribe button. With the "one-click" version (RFC 8058) the app unsubscribes the person without opening a web page.

Metrics#

Term	What it means
Open rate	Unique opens ÷ delivered emails. Opens are detected with a tiny tracking image, so privacy features that load images automatically make the number less reliable. See Open Rates + Apple MPP.
Click rate (CTR)	Unique clicks ÷ delivered emails.
Click-to-open rate (CTOR)	Unique clicks ÷ unique opens.
Bounce rate	Bounces ÷ emails sent.
Unsubscribe rate	Unsubscribes ÷ delivered emails.
Complaint rate (spam rate)	Complaints ÷ delivered emails.
Conversion rate	People who completed the goal — a purchase, a signup — divided by delivered emails or by clickers. Always say which.

"Unique" means each recipient is counted once, however many times they opened or clicked.

What to do after#

• See how these terms fit together: the other articles in Domain Knowledge explain consent, deliverability, metrics and list quality in depth.
• Read your first report with the definitions at hand: How to read your email campaign report.

♡ Sign in to like 0 💬 0 comments