Resend Integration

Resend is an alternative email provider you can use with Mailer. While AWS SES is the default provider, Resend offers a simpler setup process with a developer-friendly API.

Note: Resend is not the default provider. You'll need to configure it explicitly to use it.

Why Use Resend?

Simple setup - Get started in minutes with minimal configuration
Developer-friendly - Clean API and excellent documentation
Built-in analytics - Access delivery metrics in the Resend dashboard

Setup Guide

1. Create a Resend Account

Go to resend.com and sign up for an account.

2. Get Your API Key

Navigate to API Keys in your Resend dashboard
Create a new API key
Copy the key (starts with re_)

Security Tip: Create a key with only "Send emails" permissions for production use.

3. Configure Environment Variables

Add Resend as your email provider:

# Set Resend as the default provider
DEFAULT_EMAIL_PROVIDER=resend

# Your Resend API key
RESEND_API_KEY=re_xxxxxxxxxxxxx

4. Add Your API Key to Mailer (Optional)

For per-organization API keys:

Go to your Organization Settings
Find the "Email API Key" section
Paste your Resend API key
Click Save

This allows different organizations to use different Resend accounts.

Setting Up Custom Domains

Add Domain to Resend

Go to resend.com/domains
Click Add Domain
Enter your domain name
Add the DNS records provided by Resend

Required DNS Records

Resend will provide you with:

Type	Purpose
TXT (SPF)	Email authentication
TXT (DKIM)	Email signing
TXT (DMARC)	Domain policy (recommended)

Add these records to your DNS provider (Cloudflare, Route53, Namecheap, etc.).

Verify Domain

Return to resend.com/domains
Wait for DNS propagation (usually 24-48 hours)
Status will change to "Verified" when ready

Use Custom Domain in Mailer

Once verified:

Go to Organization Settings → Domains
Add your verified domain
Select "resend" as the provider
Click Set Active

Switching Between Providers

You can use both SES and Resend in the same Mailer installation:

Set different providers per domain
Use SES as default, Resend for specific organizations
Migrate gradually by switching domains one at a time

To switch a domain's provider:

Go to Organization Settings → Domains
Edit the domain
Change the provider setting
Save changes

Troubleshooting

Domain Not Verifying

Check DNS records are correctly added
Wait 24-48 hours for propagation
Verify TXT record format is correct
Use MXToolbox to check DNS

API Key Not Working

Verify the key is correctly pasted (no extra spaces)
Check key has "Send emails" permission
Ensure key hasn't been revoked in Resend dashboard
Confirm DEFAULT_EMAIL_PROVIDER=resend is set

Emails Not Sending

Check the Resend dashboard for error logs
Verify domain is verified in Resend
Ensure recipient email is valid
Check application logs for detailed errors

Low Deliverability

Ensure SPF, DKIM, DMARC are all configured
Clean your email lists regularly
Warm up new domains gradually
Monitor and remove hard bounces