Email Reply Builder
Reply to emails from your own custom domain and keep the full conversation history intact. Paste the original email, write your reply, and send it through Resend â the history is preserved automatically.
The original email is parsed in your browser. Your Resend API key is used only for this send request and is not stored or logged.
Raw email
Copy from Gmail Show original or Outlook View Source.
Parsed context
Paste raw email to see thread headers and sender mapping.
Your reply
Send with Resend
Enter the reply subject.
Enter the email address to reply to.
Used only for this send request. Not stored or logged.
Use a sender address from a verified Resend domain
Optional. Total attachments up to 9.0 MB.
How it works
Paste Raw Email
Automatically extract thread info like sender, subject, Message-ID, and References.
Write Your Reply
Optionally quote the original email content in your response.
Send via Resend
Use your verified sending domain and keep the original email conversation thread.
Use cases
Custom Domain Replies
Reply with your custom domain to emails forwarded via Cloudflare Email Routing.
Keep Email Threads
Ensure your replies stay within the original conversation instead of creating isolated emails.
Quick Business Reply
No full mail client configuration needed â ideal for lightweight routing reply needs.
Team Collaboration
Useful for support, sales, and project conversations that need consistent email replies.
Privacy and data handling
Your email content is processed in the browser. Only the reply text and any attachments you choose to include are sent when you click send.
No Content Retention
The browser parses the raw email locally, and the send request forwards only the composed payload you submit. We do not persist the raw email, reply text, attachments, or API key.
Browser-side Parsing
Your raw email structure is parsed locally in the browser, ensuring complete privacy.
Ephemeral API Keys
Your Resend API key stays in browser memory and is used only for the current send request.
FAQ
Usually, yes. Correct In-Reply-To and References headers are set, though final threading relies on the recipient's mail client (e.g. Gmail).
No. The key stays in browser memory for the current request and is sent to Resend through the API proxy without being persisted.
Yes. Files are converted locally to Base64 format and sent directly within Resend's payload size limits.
Check the Resend API key, verify that your sending domain is approved, confirm the reply target address, and make sure attachments are within the limit. The page will show the returned error.
Standalone open-source version
A standalone open-source version is available on GitHub. The hosted Easton Tools version and the GitHub version are maintained separately. You can inspect, run, self-host, or adapt the GitHub version for your own use.