Resend Integration

This document explains how the Resend email service is integrated for sending transactional emails.

Configuration

1. Provider Selection: To use Resend, the NEXT_PUBLIC_EMAIL_PROVIDER environment variable must be set to "resend". This can be done via the configuration UI (/configure) or directly in the .env file.

2. API Key: The RESEND_API_KEY environment variable must contain a valid API key obtained from your Resend account.

How it Works

When NEXT_PUBLIC_EMAIL_PROVIDER is set to "resend", the core email router calls the Resend-specific sending logic located in src/server/email/send-email-resend.ts.

This logic:

• Uses the official resend SDK.
• Checks if RESEND_API_KEY is configured (isResendConfigured).
• Takes a payload (EmailPayload) containing to, subject, from, and either react (a React Email component) or text.
• Renders React components to HTML using @react-email/render.
• Handles both single recipient sends (resend.emails.send) and batch sends (resend.batch.send) if to is an array.
• Includes error handling and logging for API responses.

Usage Examples

When Resend is configured as the provider, it's used by the core sendEmail function for actions like:

• Sending email verification links.
• Sending password reset links.
• Sending email change confirmations (if enabled).

Considerations

• Pricing and Limits: Resend offers various plans including a free tier with limitations. Refer to the official Resend Pricing for details.
• Daily Sending Limit: Be aware of potential sending limits, especially on the free tier. See the General Email Configuration for discussion and mitigation strategies.
• Domains: Configure sending domains within your Resend account dashboard.
• Data Retention: Check your Resend plan for details on email log retention periods.