Stalwart SMTP Server
Stalwart SMTP is 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.
- Sender and Message Authentication:
- Domain-based Message Authentication, Reporting, and Conformance (DMARC) verification and failure/aggregate reporting.
- DomainKeys Identified Mail (DKIM) verification, signing and failure reporting.
- Sender Policy Framework (SPF) policy evaluation and failure reporting.
- Authenticated Received Chain (ARC) verification and sealing.
- Reverse IP (iprev) validation.
- Strong Transport Security:
- DNS-Based Authentication of Named Entities (DANE) Transport Layer Security.
- SMTP MTA Strict Transport Security (MTA-STS).
- SMTP TLS Reporting (TLSRPT) delivery and analysis.
- Inbound Filtering and Throttling:
- Sieve scripting language with support for all registered extensions.
- Filtering, modification and removal of MIME parts or headers.
- DNS block lists (DNSBL) & Greylisting.
- Inbound concurrency & rate limiting.
- Integration with external content filtering systems such as SpamAssassin and ClamAV.
- Flexible Queues:
- Unlimited virtual queues with custom routing rules.
- Delayed delivery with
- Priority delivery with
- Outbound throttling & Disk quotas.
- Logging and Reporting:
- Detailed logging of SMTP transactions and events, including delivery attempts, errors, and policy violations.
- Integration with OpenTelemetry to enable monitoring, tracing, and performance analysis of SMTP server operations.
- Automatic analysis of incoming DMARC/TLS aggregate reports, DMARC/DKIM/SPF authentication failure reports as well as abuse reports.
- And more:
- SASL authentication.
- PostgreSQL, MySQL, MSSQL and SQLite support.
- Granular configuration rules.
- REST API for management.
- Memory safe (thanks to Rust).
Install Stalwart SMTP on your server by following the instructions for your platform:
You may also compile Stalwart SMTP from the source.
If you are having problems running Stalwart SMTP, you found a bug or just have a question, do not hesitate to reach us on Github Discussions, Reddit or Discord. Additionally you may become a sponsor to obtain priority support from Stalwart Labs Ltd.
Table of Contents
- Get Started
- Inbound settings
- Outbound settings
- Email Authentication