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Email marketing glossary

The words you'll meet, in plain language. Link straight to any term.

A

A/B test
Sending two versions of an email (say, two subject lines) to small parts of your list to see which performs better, then sending the winner to everyone else.
Alt text
A short written description of an image. It's shown when images don't load and read aloud by screen readers, so it should say what the image shows.
Automation
An email (or series) that sends itself when something happens, such as a welcome email when someone joins your list.

B

Bounce (hard and soft)
An email that couldn't be delivered. A hard bounce is permanent (the address doesn't exist) and the address should never be emailed again. A soft bounce is temporary, such as a full mailbox.
Bounce rate
The share of sent emails that bounced. A high bounce rate usually means an old or unverified list, and it hurts your sender reputation.

C

Call to action (CTA)
The thing you want the reader to do next, usually a button such as "Book now" or "Read the story".
Campaign
One email sent to a chosen group of people at one time, such as a monthly newsletter or a sale announcement.
Click-through rate (CTR)
The share of delivered emails in which someone clicked at least one link. It's the most reliable measure of interest.
Click-to-open rate
Of the people who opened an email, the share who also clicked. It tells you how well the content itself worked.

D

Deliverability
How reliably your emails reach the inbox rather than the spam folder. It depends on authentication (SPF, DKIM, DMARC) and on how people react to your emails.
DKIM
A digital signature added to every email you send, checked by the receiving inbox against a public key in your domain's DNS. It proves the email really came from your domain and wasn't altered.
DMARC
A DNS record that tells inboxes what to do with email that fails SPF or DKIM checks for your domain: nothing (p=none), spam folder (quarantine) or reject. Gmail and Yahoo expect bulk senders to have one.
Double opt-in
Signing up in two steps: the person fills in a form, then confirms by clicking a link in an email. It proves the address is real and belongs to them.

H

Hard bounce
See Bounce: a permanent delivery failure, such as an address that doesn't exist.

L

List hygiene
Keeping your list healthy: removing addresses that bounce, honouring unsubscribes and not emailing people who haven't engaged in a very long time.

M

Merge tag
A placeholder that's replaced with each person's details when the email is sent, such as their first name in the greeting.

O

Open rate
The share of delivered emails that were opened. Treat it as a rough signal only: some email apps open emails automatically for privacy reasons, which inflates it.

P

Preview text
The short line many inboxes show next to or under the subject. Use it to add to the subject, not repeat it.

S

Segment
A part of your list chosen by a rule, such as everyone with a certain tag or everyone who joined through a particular form.
Sender reputation
How trustworthy inbox providers consider your sending domain to be, based on bounces, spam complaints and engagement over time.
Sending domain
The domain your emails come from (the part after @). Sending from your own, verified domain looks more professional and builds your own reputation.
Spam complaint
When a recipient clicks "Report spam". Even a few complaints per thousand emails can push your emails into spam folders.
SPF
A DNS record listing the services allowed to send email on behalf of your domain.
Subject line
The headline of your email in the inbox. Specific and honest subject lines get opened; misleading ones get reported.
Suppression list
Addresses you must not email again, such as people who unsubscribed, bounced permanently or reported spam.

U

Unsubscribe
Opting out of your emails. Every marketing email must include an easy way to do it, and requests must be honoured promptly.