# The Email Glossary.

## Clear, simple definitions of the terms every developer and marketer needs to know about email delivery, APIs, and authentication.

[**Transactional Email** 
Automated emails triggered by user actions such as signups, password resets, or purchase confirmations.](/content/glossary/transactional-email/index.html)

[**Marketing Email** 
Emails sent to promote products, services, or updates to a group of subscribers, including newsletters and promotions.](/content/glossary/marketing-email/index.html)

[**SMTP (Simple Mail Transfer Protocol)** 
The standard protocol used to send emails across the internet.](/content/glossary/smtp-simple-mail-transfer-protocol/index.html)

[**Email API** 
A developer interface that allows applications to send and manage emails programmatically without manual SMTP setup.](/content/glossary/email-api/index.html)

[**DKIM (DomainKeys Identified Mail)** 
An authentication method that verifies an email's integrity and sender domain using cryptographic signatures.](/content/glossary/dkim-domainkeys-identified-mail/index.html)

[**SPF (Sender Policy Framework)** 
A DNS record that specifies which servers are authorized to send emails for a domain, preventing spoofing.](/content/glossary/spf-sender-policy-framework/index.html)

[**DMARC (Domain-based Message Authentication, Reporting & Conformance)** 
An authentication protocol that builds on SPF and DKIM, telling mail servers how to handle failed authentication.](/content/glossary/dmarc-domain-based-message-authentication-reporting-conformance/index.html)

[**Bounce Rate** 
The percentage of emails that fail to deliver. Hard bounces are permanent, soft bounces are temporary.](/content/glossary/bounce-rate/index.html)

[**Email Deliverability** 
A measure of how successfully emails reach recipients' inboxes instead of spam folders.](/content/glossary/email-deliverability/index.html)

[**Inbox Placement** 
Whether emails land in the primary inbox, promotions tab, or spam folder.](/content/glossary/inbox-placement/index.html)

[**Open Rate** 
The percentage of recipients who open an email, influenced by subject line, sender reputation, and placement.](/content/glossary/open-rate/index.html)

[**Click-through Rate (CTR)** 
The percentage of recipients who click links inside an email.](/content/glossary/click-through-rate-ctr/index.html)

[**Suppression List** 
A list of email addresses that should never receive emails, including unsubscribes, bounces, and spam complaints.](/content/glossary/suppression-list/index.html)

[**Global Unsubscribes** 
Addresses that opted out of receiving any emails from your account or domain, across all campaigns and lists.](/content/glossary/global-unsubscribes/index.html)

[**Unsubscribe Groups** 
Categories that allow recipients to selectively unsubscribe from certain types of emails instead of all communication.](/content/glossary/unsubscribe-groups/index.html)

[**Reported Spam** 
Addresses that flagged your emails as spam. Automatically suppressed to protect sender reputation.](/content/glossary/reported-spam/index.html)

[**Invalid Emails** 
Email addresses that don't exist or are incorrectly formatted, causing permanent delivery failures.](/content/glossary/invalid-emails/index.html)

[**Bounced Emails** 
Emails that could not be delivered. Hard bounces are permanent, soft bounces are temporary.](/content/glossary/bounced-emails/index.html)

[**Blocked Emails** 
Emails rejected by receiving servers due to IP reputation, blacklisting, or policy restrictions.](/content/glossary/blocked-emails/index.html)

[**Email Warmup** 
The process of gradually increasing email volume on a new IP or domain to build reputation.](/content/glossary/email-warmup/index.html)

[**Dedicated IP vs Shared IP** 
Dedicated IPs are used only by one sender; shared IPs are used by multiple accounts with shared reputation.](/content/glossary/dedicated-ip-vs-shared-ip/index.html)

[**List Hygiene** 
The practice of cleaning email lists by removing invalid or unengaged addresses to improve deliverability.](/content/glossary/list-hygiene/index.html)

[**MX Record** 
A DNS record that directs emails to the correct mail server for receiving messages.](/content/glossary/mx-record/index.html)

[**Email Service Provider (ESP)** 
A company or platform that offers tools to send, manage, and track email campaigns, such as AutoSend, Mailchimp, or SendGrid.](/content/glossary/email-service-provider-esp/index.html) 
  
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