vSMTP is a next-gen Mail Transfer Agent (MTA), faster, safer and greener.

• It is 100% built in Rust.
• It is lighting fast.
• It is modular and highly customizable.
• It has a complete filtering system.
• It is actively developed and maintained.

While optimizing IT resources becomes an increasing challenge, computer attacks remain a constant problem.

Every day, over 300 billion emails are sent and received in the world. Billions of attachments are processed, analyzed and delivered, contributing to the increase in greenhouse gas emissions.

To meet these challenges, viridIT is developing a new technology of email gateways, also called vSMTP.

Follow us on viridit.com

vSMTP enable you to create complex set of rules to filter your emails using the vsl programming language based on Rhai. You can:

• inspect / modify the content of incoming emails.
• forward and deliver emails locally or remotely.
• connect to databases.
• run commands.
• quarantine emails.

and much more.

// -- database.vsl
// here we declare our services.
// connect to a database with the csv format.
service greylist db:csv = #{
  connector: "/db/greylist.csv",
  access: "O_RDWR",
  refresh: "always",
  delimiter: ',',
};

// -- main.vsl
// here we declare our rules for filtering.

import "database" as db;

#{
  // hook on the 'mail from' stage.
  mail: [
    // you can decide to accept or deny an email with a "rule".
    rule "greylist" || {

      let sender = ctx().mail_from;

      // is the user in our greylist ?
      if db::greylist.get(sender).len() != 0 {
        // it is, we accept the email.
        accept()
      } else {
        // it does not, we add the address to the database, then deny the email.
        db::greylist.set([ sender ]);
        deny()
      }
    }
  ],

  // hook on delivery, just before emails are sent to all recipients.
  delivery: [
    // you can setup delivery, log information, dump an email etc ... with an "action"
    action "setup delivery" || {

      log("info", `setting up delivery for ${ctx().client_ip}`);

      // forward all recipients with the 'example.com' domain.
      for rcpt in ctx().rcpt {
        if rcpt.domain is "example.com" {
          forward(rcpt, "mta.example.com");
        } else {
          deliver(rcpt);
        }
      }

    }
  ]
}

For documentation please consult the vBook, the online reference and user guide for vSMTP.

To stay tuned, ask questions and get in-depth answers feel free to join our Discord server. You can also open GitHub discussions.

vSMTP is currently under development.

The next release "1.1.x" will focus on sender authentication mechanisms (SPF, NullMX records, etc.) and on security delegation via SMTP. You can find more information about the project agenda in the roadmap.

A guideline about contributing to vSMTP can be found in the contributing section.

For any question related to commercial, licensing, etc. you can contact us on our website.

The standard version of vSMTP is free and under an Open Source license.

It is provided as usual without any warranty. Please refer to the license for further information.