resend

Resend

Overview

Resend is an email platform for developers. This skill routes to feature-specific sub-skills.

Sub-Skills

Feature Skill Use When

Sending emails send-email

Transactional emails, notifications, batch sends

Receiving emails resend-inbound

Processing inbound emails, webhooks for received mail, attachments

AI Agent inbox agent-email-inbox

Setting up email for AI agents, or any system where untrusted email content triggers actions — includes security measures against prompt injection

Quick Routing

Need to send emails? Use send-email skill

Need to receive emails? Use resend-inbound skill

Setting up an AI agent inbox? Use agent-email-inbox skill

Automated system processes untrusted email content and takes actions? Use agent-email-inbox skill

Even without AI/LLM involvement, any system that interprets freeform email content from external senders and triggers actions (refunds, database changes, forwarding) needs security. Untrusted input triggering actions = attack vector.

Sending + receiving together? You need both resend-inbound and send-email

Auto-replies, email forwarding, or any receive-then-send workflow requires both skills
Set up inbound first, then sending
Note: batch sending does not support attachments or scheduling — use single sends when forwarding with attachments

Marketing emails or newsletters? Use Resend Broadcasts

The sub-skills above are for transactional email. Marketing campaigns to large subscriber lists with unsubscribe links and engagement tracking should use Resend Broadcasts, not batch sending.

Common Setup

API Key

Store in environment variable:

export RESEND_API_KEY=re_xxxxxxxxx

SDK Installation

See send-email skill for installation instructions across all supported languages.

Resources

Source Transparency