Dev tools · alternatives · 2026

24 alternatives to SMTP Server in Rust with DMARC, Dane, MTA-STS, Sieve, OTEL Support

I am happy to announce Stalwart SMTP [1], a modern SMTP server developed in Rust with a focus on security, speed, and extensive configurability. It features built-in DMARC, DKIM, SPF and ARC support for message authentication, strong transport security through DANE, MTA-STS and SMTP TLS reporting, and offers great flexibility and customization thanks to its dynamic configuration rules and native support for Sieve scripts. The project has been recently awarded a grant from NLNet and the European Commission's Next Generation Internet program to develop a mail server in Rust. The next step in…

Stalwart SMTP is a mail server written in Rust that handles email authentication through DMARC, DKIM, SPF, and ARC protocols. It provides transport security via DANE and MTA-STS, supports Sieve scripting for message… Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes. SMTP Server in Rust with DMARC, Dane, MTA-STS, Sieve, OTEL Support launched in 2023; newer entries below may have overtaken it.

1
Distributed JMAP and IMAP Servers in Rust▲190
I am happy to announce Stalwart JMAP [1], an open-source JSON Meta Application Protocol server that aims to be scalable, robust and secure. Some of its key features are: - JMAP Core, JMAP Mail and JMAP over WebSocket full compliance. - IMAP4 rev2/1 support via Stalwart IMAP, an imap-to-jmap proxy [2]. - Scalable and fault tolerant: consensus over Raft, node autodiscovery over gossip and read-only replicas. - RocksDB backend with full-text search support in 17 languages. - OAuth 2.0 authorization code and device authorization flows. - Domain Keys Identified Mail (DKIM) message signing. -…
2022 · github.com · its alternatives →
2
VaultSandbox – Test your real MailGun/SES/etc. integration▲58
I've spent the last few months working on something I wish I'd had years ago. I kept running into the same issue: CI green, production mail broken. TLS handshake failures, DKIM alignment mismatches, SPF soft-fails ... the stuff that only surfaces when real mail servers are involved. Most test tools (Mailpit, MailHog) are catch-alls. They confirm "an email was sent" but don't validate the protocol. They also aren't designed for network-exposed environments: no auth, unprotected Web UI, easy to enumerate messages. VaultSandbox is my attempt at fixing that. It's a self-hosted SMTP gateway…
Jan 2026 · vaultsandbox.com · its alternatives →
3
MCP-stama – An ultra-fast Rust MCP server with no dependencies▲73
An ultra-fast, single-binary MCP server written in Rust as a lightweight alternative to Node.js/Python. - StamManif/mcp-stama
Aug 2026 · github.com · its alternatives →
4
I built a DNS resolver from scratch in Rust – no DNS libraries▲115
I built a DNS resolver that lets me use https://frontend.numa instead of localhost:5173 — auto-generated TLS certs, WebSocket passthrough, path routing. No mkcert, no nginx, no /etc/hosts.
Apr 2026 · github.com · its alternatives →
5
Second State VM▲78
High performance secure & portable Rust functions in Node.js
2020 · secondstate.io · its alternatives →
6
Cap'n-rs – Rust implementation of Cloudflare's Cap'n Web protocol▲52
Last week Cloudflare released Cap'n Web [1], a schema-free capability-based RPC protocol. I built capn-rs this week - a Rust implementation with full wire protocol compatibility. Links: GitHub: https://github.com/currentspace/capn-rs Crates: https://crates.io/crates/capnweb-server API docs: https://docs.rs/capnweb-server What's working: Wire compatibility verified via integration tests against TypeScript reference Multi-transport: HTTP batch, WebSocket, WebTransport (HTTP/3) Complete IL (intermediate language) expression evaluator…
2025 · github.com · its alternatives →
7
RustMailer▲4
A self-hosted IMAP/SMTP middleware designed for developers
2025 · rustmailer.com · its alternatives →
8
SMTP Tunnel – A SOCKS5 proxy disguised as email traffic to bypass DPI▲140
A fast SOCKS5 proxy that tunnels your traffic through what looks like normal SMTP email, bypassing Deep Packet Inspection firewalls. How it works: - Client runs a local SOCKS5 proxy (127.0.0.1:1080) - Traffic is sent to server disguised as SMTP (EHLO, STARTTLS, AUTH) - DPI sees legitimate email session, not a VPN/proxy Features: - One-liner install on any Linux VPS - Multi-user with per-user secrets and IP whitelists - Auto-generated client packages (just double-click to run) - Auto-reconnect on connection loss - Works with any app that supports SOCKS5 Tech: Python/asyncio, TLS…
Jan 2026 · github.com · its alternatives →
9
Stalwart Mail Server
Secure & Modern All-in-One Mail Server (IMAP, JMAP, SMTP)
2024 · its alternatives →
10AF
A fake SMTP server for software integration testing▲127
This is a side project of mine. Use this as your SMTP server in a test environment to guarantee that your users don't receive test emails. Looking for feedback, especially on the security side.
2024 · fakemail.stream · its alternatives →
11
Stalwart JMAP/IMAP Server▲2
Distributed JMAP and IMAP server written in Rust.
2022 · stalw.art · its alternatives →
12
I'm rewriting a web server written in Rust for speed and ease of use▲68
Hello! I got quite some feedback on a web server I'm building, so I'm rewriting the server to be faster and easier to use. I (and maybe some other contributors?) have optimized the web server performance, especially for static file serving and reverse proxying (the last use case I optimized for very recently). I also picked a different configuration format and specification, what I believe is easier to write. Automatic TLS is also enabled by default out of the box, you don't need to even enable it manually, like it was in the original server I was building. Yesterday, I released the first…
2025 · ferron.sh · its alternatives →
13
Localdots – HTTPS domains for localhost with autoconfig and hot reload▲75
HTTPS domains for localhost. 🏠. Contribute to lufzle/localdots development by creating an account on GitHub.
2019 · github.com · its alternatives →
14
MailCue▲82
Run as a fully hardened production email server.
Apr 2026 · olib-ai.github.io · its alternatives →
15
Posthorn, self-hosted mail gateway▲83
Introducing Posthorn, a self hosted email gateway. One docker container (or Go binary) between every self hosted app on your VPS and your transactional email provider. Set up Posthorn once, point your apps to it, done. I was trying to deploy Ghost on a DigitalOcean droplet and found that DO and many different VPS services have started to block the default SMTP ports to try to combat the various types of abuse they get. To actually configure my app, I had to hack together a Postfix relay. In another project, I had a static site which had a contact form, but my free Formspree account was…
May 2026 · github.com · its alternatives →
16
An Elliptic Curve-Based Secure Chat, Written Using Rust and Protobuf▲66
This is a project I made to learn more about crypto. I've also written a [post](https://vaktibabat.github.io/posts/ecurvechat/) that explains all the crypto concepts and algorithms used in the project, and how I implemented them. I'd be very glad for any feedback about both the code and the post :)
2024 · github.com · its alternatives →
17
A Language Server Implementation for SystemD Unit Files▲78
A Language Server Protocol (LSP) implementation for systemd unit files, providing editing support with syntax highlighting, diagnostics, autocompletion, and documentation made with rust.
2025 · github.com · its alternatives →
18
Sklad – Secure, offline-first snippet manager (Rust, Tauri v2)▲22
Hi HN, I’m Pavel. I built Sklad because, as a DevOps engineer, I was frustrated with how I handled operational data. I constantly need access to SSH passwords (where keys aren't an option), specific IP addresses, and complex CLI one-liners. I realized I was storing them in insecure text files or sticky notes because standard clipboard managers felt too bloated and password managers were too slow for my workflow. I wanted a "warehouse" for this data—something that lives quietly in the system tray, supports deep hierarchy, works completely offline, and looks industrial. The app is built with…
Feb 2026 · github.com · its alternatives →
19
A simple, pretty alternative to strace written in Rust▲36
A pretty (simple) alternative to strace. Contribute to JakWai01/lurk development by creating an account on GitHub.
2022 · github.com · its alternatives →
20
S3 compatible store with 1M IOPS(4K-R,p99~5ms), BYOC in 5min with rust▲23
Ultra-high performance distributed storage system in the AI era. Powered by Fractal ART engine, Rust-native, io_uring, with multi-protocol (S3 object storage, POSIX FS, ...) - fractalbits-labs/fractalbits
Dec 2025 · github.com · its alternatives →
21
JSON-Threat-Protection Rust High-Performance Crate▲34
A crate to protect against malicious JSON payloads. - ADD-SP/json-threat-protection.rs
2024 · github.com · its alternatives →
22
HTTPS-DNS - Rust-based minimal DNS-over-HTTPS (DoH) client▲14
2022 · github.com · its alternatives →
23
Rapid-rs – Zero-config web framework for Rust▲9
Hi HN! I built rapid-rs to solve a problem I kept hitting: setting up a new Rust web API requires wiring together lots of crates and boilerplate. : FastAPI's developer experience + Spring Boot's conventions, with Rust's performance and type safety. : - One command to scaffold: `rapid new myapi` - Auto-configuration: DB, logging, CORS work out of the box - Type-driven validation: Compile-time + runtime guarantees - Auto-generated OpenAPI/Swagger UI - Built on Axum, so you can use Axum patterns when needed It's early stage but functional. Would love feedback from the HN community! GitHub:…
Nov 2025 · crates.io · its alternatives →
24
Tysm, a Rust crate for using ChatGPT with Structured Outputs▲7
Hi HN! This Christmas I made `tysm`, a rust crates which simplifies using ChatGPT with Structured Outputs. Essentially you just tell it the rust type you want the output to conform to, and it handles creating the JSON Schema, passing it to ChatGPT's chat-completions API, and deserializing the response. Structured Outputs are very useful because they guarantee that the response will conform to whatever type you expect. I'm already finding my crate very useful since I love using Structured Outputs but I hate writing JSON Schemas myself. Technical details for rust heads: To generate the JSON…
2024 · github.com · its alternatives →

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Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →