Email marketing has its own vocabulary. This page is a simple reference for the terms that come up most often when you are cleaning a list, sending campaigns, or diagnosing deliverability issues.
A
Authentication The technical setup that helps receiving systems trust your email, usually through SPF, DKIM, and DMARC.
B
Bounce An email that could not be delivered.
Bounce rate The percentage of sent emails that bounced.
Blocklist A reputation list used by some systems to identify known spam sources.
C
Catch-all domain A domain that accepts mail for many or all addresses, even when the exact mailbox situation is unclear.
Click-through rate The percentage of delivered emails that generated a click.
D
Deliverability The broader question of whether your email reaches the inbox instead of spam or rejection.
Disposable email A temporary address used for short-term signups.
Double opt-in A signup flow that asks the subscriber to confirm their address before being added fully to the list.
E
Email validation The process of checking whether an address looks usable based on formatting and mail-related signals.
ESP An email service provider such as Mailchimp, Klaviyo, Brevo, or ConvertKit.
H
Hard bounce A permanent delivery failure.
L
List decay The natural process of email data going stale over time.
List hygiene The ongoing practice of keeping a list healthier by removing or isolating bad data.
M
MX record A DNS record that points to the mail servers responsible for receiving email for a domain.
O
Open rate The percentage of delivered emails that registered as opened. It is directionally useful, but not a perfect truth metric.
R
Role-based address An address like info@, support@, or billing@ that represents a function rather than one person.
S
Sender reputation The trust signal built from your sending history, complaints, bounces, and engagement.
Soft bounce A temporary delivery failure.
Spam trap A monitoring address used to identify poor list hygiene practices.
Sunset policy A rule for reducing or removing long-unengaged contacts over time.
W
Warm-up The process of increasing sending volume gradually so your setup does not look suspicious to inbox providers.
If a term keeps appearing in email conversations, it is usually because it affects either list quality, deliverability, or reporting. Those three areas are more connected than they look.