Email marketing glossary

Practical email marketing knowledge

Email marketing glossary

What does SMTP mean? How do you calculate a newsletter unsubscribe rate? This glossary explains key terms in email marketing, delivery, and reporting.

Fundamentals

What is email marketing?

Common email marketing formats and how businesses use them.

What is a newsletter?

How a newsletter is structured and what it can do.

What is an email subject line?

What makes a newsletter subject line clear.

Sending and deliverability

What is SMTP?

How emails travel from one mail server to another.

What is sender reputation?

The signals that shape an email sender’s reputation.

What is an email allowlist?

How an allowlist can affect email delivery.

What is an email blocklist?

How blocklists work and how to check whether a sender is listed.

What is a spam filter?

The signals email providers use to filter messages.

What is spam?

How to recognize unwanted bulk email.

Reporting and optimization

What is the newsletter unsubscribe rate?

The unsubscribe rate, with a formula and worked example.

What is A/B testing in email marketing?

How to compare two newsletter variants fairly.

What is the spam complaint rate?

How to interpret spam reports and calculate a complaint rate.

Contacts and personalization

What are email personalization placeholders?

How contact data appears in email copy and subject lines.

What is email list hygiene?

How to spot invalid addresses and duplicates.

What is an email suppression list?

How a sending tool excludes suppressed recipients.

Newsletter content

What are HTML and plain-text versions of a newsletter?

How one email can remain readable in both HTML and plain text.

What is a newsletter’s web version?

When a “View in browser” link is helpful.

What is alt text in a newsletter?

How to describe informative images and label image links.

Email technology and automation

What is a transactional email?

When an email relates to a specific transaction or account action.

What is an autoresponder?

How an event triggers an automated email.

What is an email header?

Which technical details help you troubleshoot email.