How It Works
Email in, JSON out. No SMTP required.
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JSON-Native API
No SMTP libraries, no protocol wrangling. Emails arrive as structured JSON via HTTP POST — parse them with standard library tools in any language your serverless platform supports.
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Outbound SPF, DKIM & DMARC
Outbound emails are signed with SPF, DKIM and DMARC by default. Custom hardened email servers with 99.99% uptime.
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Zero Infrastructure
No mail servers, no SMTP credentials, no connection pooling. Your function receives a webhook, processes it, and returns. Start free and scale to millions of emails per month.
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Receive Email via Webhook
CloudMailin receives your email, validates SPF by default and optionally verifies DKIM and DMARC. It parses headers, body, and attachments, then delivers the result as a structured JSON HTTP POST to your serverless function.
Choose JSON, Multipart, or RAW format — whatever suits your stack. Emails are processed and delivered in seconds, ready to handle in Lambda, Cloud Functions, or any endpoint that accepts HTTP.
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Send Email via HTTP or SMTP
Sending transactional email from a serverless function? CloudMailin's outbound API accepts a simple HTTP POST with JSON — no SMTP client needed. DKIM signing, SPF alignment, and bounce management are handled automatically.
Need SMTP instead? That works too. Use whichever protocol fits your platform. Either way, you get delivery tracking, open rates, and detailed logs in the dashboard.
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Offload Attachments to Cloud Storage
Serverless functions have payload limits. CloudMailin can offload attachments to Amazon S3, Google Cloud Storage, or Azure Blob Storage before they reach your function.
Your webhook receives a URL to each file — keeping payloads small and your functions fast. Process attachments asynchronously on your own schedule.
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Works with Every Serverless Platform
AWS Lambda, Google Cloud Functions, Azure Functions, Cloudflare Workers, Vercel, Netlify — CloudMailin works with whatever you're building on. Emails arrive as standard HTTP POSTs, so there's nothing platform-specific to learn.
Node.js, Python, Go, Rust, Ruby — use any language your platform supports. Integration takes minutes, not days.
Testimonials
Don't just take our word for it
Andreas Santoro
CTO, ExpressSteuer
CloudMailin has been instrumental in our growth at ExpressSteuer. The system is not only incredibly easy to implement, but also highly reliable and robust. What's more, their support team is simply amazing - always quick to respond and provide effective solutions to any challenge we encounter. We couldn't be more pleased with the service provided by CloudMailin!
Dan
CamelCamelCamel.com
Thanks for the rock solid decade
Francisco (Kiko) R.
Head of Engineering, ProFinda.com
The product is perfect, feature rich, nice and intuitive UI and great support. It was really easy to integrate it into our application. It enables our application to receive inbound traffic, to give better support to clients and to expand our mailing options.
Developer Support from Email Experts
Whether you're a solo developer prototyping on Lambda or an engineering team processing millions of messages, you get the same direct support from our team of email infrastructure experts. No bots — just real people who know email inside and out. You can even reach us by phone when you need to.
Ready to add email to your serverless stack?
Get started in minutes. Your first 10,000 emails per month are free.
No SMTP. No servers. Just JSON.