RustMailer
Self-hosted Email API Server built with Rust.
Hi Indie Hackers,
I’m excited to share a milestone today — we just received our first Unlimited License – Yearly Subscription (€430/year) through Stripe! 🎉
This means a lot to me because:
It validates the work I’ve been putting into RustMailer.
It shows that someone is willing to commit long-term to our product.
It gives us confidence to keep building and improving.
I want to say a big thank you to our first customer for the trust and support. 🙏
If you’re curious, we’re building RustMailer — an open-source email sync engine (Gmail API + IMAP) designed for speed, reliability, and zero-hassle integration.
Would love to hear your feedback or suggestions — and if you’ve also just gotten your first paid subscriber, please share your story below! 💬
—
Billy Dong
Founder
I registered a Reddit account around 11 PM Tokyo time and posted about RustMailer 1.0 in the r/selfhosted subreddit.
I briefly listed the features and gave some background about the project.
In the next 2–3 hours, the post got over 7,000 views and even received a couple of comments. I replied to one of them.
But when I checked again later that night, my post was gone — and my account had been permanently suspended.
I'm completely confused. What happened?
Did introducing my own project and linking to GitHub somehow violate Reddit's rules?
There was no warning before posting, no message after registering, and no explanation after the ban.
At this moment, I honestly feel a bit defeated. What’s going on?
https://rustmailer.com/docs/blog/integrate-rustmailer-search-crm
🔍 API Purpose
The RustMailer /unified-search API enables rapid email searches within a local cache, supporting queries based on email address, time range, and account scope. This API avoids real-time IMAP server connections by leveraging a pre-built index table, making it ideal for integration with CRM systems, customer support platforms, or sales management tools.
🧠 Use Case Example: Retrieving Customer Email History in a CRM
In a CRM, you often need to:
Display recent email interactions on a customer’s profile page.
Quickly locate all communications for a customer across multiple email accounts.
Filter emails by time range or communication direction (from/to).
The /unified-search API allows your CRM to retrieve emails from multiple accounts in a unified manner without dealing with underlying IMAP protocols, delivering millisecond-level response times.
🛠️ API Definition (OpenAPI)
POST /api/v1/unified-search
Request Parameters (Query):
ParameterTypeDescriptionpageu64Current page number (starts at 1)page_sizeu64Number of emails per pagedescboolSort by time in descending order (default: ascending)
Request Body (JSON):
{
"email": "customer@example.com",
"after": 1719859200000,
"before": 1722451200000,
"accounts": [1, 2, 5]
}
after/before: Optional time range (UTC milliseconds).
accounts: Optional list of email account IDs; if omitted, includes all accessible accounts.
✅ Example Request (curl)
curl -X POST https://your-server/api/v1/unified-search?page=1&page_size=50&desc=true \
-H "Authorization: Bearer <token>" \
-H "Content-Type: application/json" \
-d '{
"email": "alice@example.com",
"after": 1720000000000,
"before": 1720500000000
}'
⚡ Performance Notes: Index-Based Fast Queries
The /unified-search API relies on RustMailer’s internal email index table, which stores metadata such as subjects, sender, recipient, and timestamps, without caching full email content or attachments during synchronization. This enables sub-second response times, even with millions of cached emails, supporting efficient paginated searches. The API returns a list of email metadata, allowing users to view a list of email subjects. When a user clicks to view an email’s content, RustMailer uses a separate API to fetch the email body and attachments from the IMAP server. These are cached on RustMailer’s local disk to avoid redundant IMAP fetches, with automatic cleanup to manage storage efficiently.
If you have any questions or need further assistance, feel free to reach out via GitHub Discussions or join our community on Discord. If you find RustMailer useful, give it a try and consider starring the project on GitHub!
Hi Indie Hackers 👋
I launched RustMailer just 9 days ago — an open-source, self-hosted email API backend written in Rust. It connects IMAP, SMTP, Webhooks, gRPC, and OpenAPI in one seamless API-driven stack.
Here’s a quick update on how the first week went:
🛠️ What’s New This Week
✅ Reworked IMAP search logic with full condition tree support
✅ Docker image + quickstart now easier to spin up
✅ Initial version of the Web UI deployed
✅ Added Discord Webhook support for new email notifications
💬 What Users Are Saying
“Can I use this to aggregate multiple inboxes into one?”
→ Yes, coming soon.
“I’d love to plug this into our CRM as a backend email engine.”
“OpenAPI + gRPC = Dev-friendly. Just what I needed.”
❤️ How You Can Support
⭐ Give it a star on GitHub: github.com/rustmailer/rustmailer
🐛 Report issues or suggest features
📢 Share it with other devs, Rustaceans, or open-source lovers
💬 Let me know what you're building and how I can help
RustMailer is here to save you months of email system plumbing. Whether you’re building a CRM, notification service, or SaaS that relies on email, RustMailer gives you full control over the stack — in one powerful Rust-based backend.
Thanks for reading — more blog posts and Discord integrations coming next week!
Cheers! 👋
– RustMailer Dev
Developers, want to seamlessly integrate email notifications into your workflows or systems? RustMailer is your go-to solution! It effortlessly connects with platforms like Discord, Slack, and more, delivering real-time email notifications. Our latest blog tutorial walks you through building a high-performance email notification system with Discord Webhooks, designed specifically for developers—simple, powerful, and efficient!
Why Choose RustMailer?
RustMailer leverages Rust’s blazing-fast performance and security, delivering a lightweight, self-contained solution. It requires no external dependencies like Redis or databases, making deployment a breeze. Whether you’re building a self-hosted mail gateway or integrating with internal tools, RustMailer’s Web UI and OpenAPI/gRPC interfaces make it easy to push new emails (e.g., customer inquiries, system alerts, or order updates) to platforms like Discord with minimal setup.
Blog Highlights
This tutorial guides you step-by-step:
Quick Setup: Create an email account in RustMailer and grab your Account ID.
Discord Integration: Set up a Webhook to push email events to your chosen channel.
Custom Notifications: Use VRL scripts to transform email data (sender, subject, attachments, etc.) into sleek Discord embeds.
API Testing: Send test emails via API to verify queue and notification results.
Advanced Features: Support for delayed sending, retry strategies, and click tracking for complex use cases.
With clear code samples and screenshots, even Rust beginners can get started quickly. RustMailer’s WYSIWYG design ensures UI actions sync seamlessly with API calls, perfect for integrating into your systems.
Try It Now!
Ready to supercharge your notification workflow? Check out the full tutorial and set up Discord notifications in just 10 minutes! Got questions or integration ideas? Drop a comment on the blog or join our GitHub discussions to collaborate with the community.
Support Us
If RustMailer sparks your interest, visit RustMailer GitHub and give us a Star ⭐—your support fuels our updates! Share your integration stories on IndieHacker to help more developers discover this lightweight, powerful tool.
Get started now and unlock the potential of system-integrated notifications with RustMailer!
Hey everyone!
I’ve just published a new blog post that walks you through integrating a Gmail account into RustMailer using OAuth2 for secure authentication and authorization. The post covers everything from creating a Google Cloud project and setting up OAuth credentials to authorizing your account and syncing emails with RustMailer. It also includes helpful tips for debugging and configuring the sync process.
This guide is perfect for developers who want to connect Gmail—or any IMAP/SMTP provider supporting OAuth2—to RustMailer.
Feel free to check it out and give it a star if you find it useful!
https://docs.rustmailer.com/blog/add-gmail-account-rustmailer
Hey Indie Hackers!
After spending years building email middleware at a top internet company, I got fed up with the complexity and frustrations of JVM languages—constant tuning, garbage collection pauses, and random crashes. So, I decided to switch gears and build something better.
That’s how RustMailer was born — a lightweight, reliable, self-hosted email API server written in Rust. It’s the product of my experience and the frustrations I wanted to leave behind.
RustMailer supports IMAP sync, SMTP send, webhooks, REST & gRPC APIs — all packed into a single binary with zero external dependencies. My goal? To create a small but powerful tool that developers can truly own and trust.
This project is still early, and while it’s not free, I welcome anyone to try it out. I’m actively evolving it based on user feedback.
Honestly, I’m currently working on this part-time and hope to earn some living income from it. If enough people find it useful and want to support it, I’d consider going full-time.
Hi, I’m RustMailer, currently living in Fukuoka, Japan — excited to connect with this community and hear your thoughts!
The project is live on GitHub:
👉 https://github.com/rustmailer/rustmailer
Thanks for reading and being part of this journey! 🙌
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