Resend

Resend

Resend is a developer-focused transactional email API. This bundle provides email sending, domain management, API key management, audience/contact lists, and delivery tracking.

Entity Hierarchy

• Account is the top-level boundary for all resources.
• Domains are verified sending domains (e.g., mail.example.com). Emails can only be sent from verified domains.
• API Keys are authentication tokens scoped to specific domains or full account access.
• Audiences are mailing lists (contact groups) for batch operations.
• Contacts are individual email addresses within an audience.
• Emails are sent messages with delivery status tracking.

Capabilities

Email sending:

• Send transactional emails with HTML or plain text content
• Send emails with attachments
• Send batch emails to multiple recipients
• Track email delivery status (sent, delivered, bounced)

Domain management:

• List verified sending domains
• Add new domains and get DNS verification records
• Remove domains and check verification status

API key management:

• List, create, and delete API keys with optional domain restrictions

Audience and contacts:

• Create and list audiences (mailing lists)
• Add, update, and remove contacts from audiences

Workflows

Send a transactional email: Specify from address (must be on a verified domain), to address, subject, and HTML body. Optionally add reply-to, CC/BCC, and attachments. The response returns a message ID for tracking.

Set up a new sending domain: Add the domain, then configure the returned DNS records (SPF, DKIM, MX) at your DNS provider. Domain status updates once DNS propagates.

Manage a contact list: Create an audience, then add contacts with email and optional metadata. Use the audience for batch sending.

Monitor delivery: After sending, retrieve the email status by ID to see if it was delivered or bounced.

Gotchas

• Verified domain required: Emails can only be sent from addresses on verified domains. Unverified domains return an error.
• Rate limits: Free tier has sending limits (100 emails/day). Production usage requires a paid plan.
• HTML content: The html field accepts raw HTML. There is no built-in template rendering.
• Batch sending: Each message in a batch is independent — no mail merge. Construct each message individually for personalization.