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· 2 min read
Mauro D.

E-mail filtering is a crucial part of any modern mail server and, for this reason, we're excited to announce the addition of Milter support to the Stalwart Mail Server. This update, driven by user feedback, allows the integration of both new and old Milter filters, supporting versions 2 and 6, which expands the server's capabilities in inspecting, filtering, or modifying emails during processing.

A milter, or "mail filter", is an extension to mail servers based on the Sendmail protocol. Milters allow third-party software to access mail messages as they are being processed in order to filter, modify, or annotate them. By using Milters, a mail server can utilize a variety of functionalities such as spam filtering, virus scanning, and other types of mail processing, beyond what is built into the mail server itself. Milters operate at the SMTP protocol level, which means they have access to both the SMTP envelope and the message contents.

This new feature not only responds to our users' needs but also ensures that Stalwart can work seamlessly with any existing setup. Whether you are seeking better spam protection, antivirus measures, or implementing specific processing rules, milter filtering has got you covered.

Learn more about milter filters and how to set them up in our documentation.

· 2 min read
Mauro D.

We're thrilled to announce the release of Stalwart Mail Server, our biggest leap forward yet. This version combines the powerful capabilities of Stalwart JMAP, Stalwart IMAP, and Stalwart SMTP servers into one easy-to-install binary, offering you a unified, highly efficient mail server solution.

Here are some of the exciting new features:

  • LDAP and SQL authentication support was added, giving you more flexibility and options to integrate Stalwart with your existing infrastructure.
  • We've incorporated support for disk quotas to provide better control over your storage resources.
  • Subaddressing and catch-all addresses are now supported. These features make the email handling process more flexible and efficient.
  • Storage options have been extended with the inclusion of S3-compatible storage. Now you can store your emails and blobs using reliable and scalable solutions such as MinIO, Amazon S3, or Google Cloud Storage.
  • In response to user feedback, we've replaced RocksDB with SQLite. Our community told us they wanted an open, trusted database technology with easier access to their data, and we listened!
  • For those operating in distributed environments, you can now opt for the FoundationDB backend, supporting millions of users without sacrificing performance.
  • Stalwart IMAP is no longer an IMAP-to-JMAP proxy, instead, it now provides direct access to the message store. This significant change has brought a tremendous improvement in performance, reducing latency, and making your mail operations faster than ever.
  • We've also made significant strides in enhancing performance by rewriting the JMAP protocol parser and the storage API.
  • Lastly, we've made the decision to switch from Actix Web Server to Hyper. This change has allowed us to reduce memory footprint and increase performance, resulting in a more optimized and efficient mail server.

With Stalwart Mail Server, we're delivering a more unified, powerful, and efficient solution that meets your growing email infrastructure needs. We're excited to see how you'll leverage these new capabilities, and as always, we're here to support you every step of the way!

· 2 min read
Mauro D.

Sieve (RFC5228) is a scripting language for filtering email messages at or around the time of final delivery. It is suitable for running on a mail server where users may not be allowed to execute arbitrary programs as it has no user-controlled loops or the ability to run external programs. Sieve is a data-driven programming language, similar to earlier email filtering languages such as procmail and maildrop, and earlier line-oriented languages such as sed and AWK: it specifies conditions to match and actions to take on matching.

Today Stalwart JMAP v0.2 was released including support for the for JMAP for Sieve Scripts draft. Additionally, ManageSieve support was added to Stalwart IMAP v0.2.

Stalwart JMAP safely runs Sieve scripts in a controlled sandbox that ensures that programs do not exceed or abuse their allocated system resources.

Unlike other mail servers that offer limited support for Sieve extensions, Stalwart JMAP supports all existing Sieve extensions including:

· One min read
Mauro D.

We are happy to announce Stalwart JMAP, an open-source JSON Meta Application Protocol server written in Rust 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.
  • 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.
  • Written in Rust.
  • No third-party software required to run or scale.

Currently Stalwart JMAP requires an SMTP server such as Postfix in order to receive e-mails. However, the next item on the roadmap is to release an SMTP server in Rust with the goal of making self-hosting an e-mail server much simpler without sacrificing any security.