A Gleam library for sending emails via SMTP, inspired by the Rust mail-send crate.
- Direct SMTP connections with TLS/SSL support
- STARTTLS and implicit TLS (port 465)
- Multiple authentication mechanisms (PLAIN, LOGIN, CRAM-MD5, XOAUTH2)
- HTML and plain text emails
- File attachments and inline images
- Custom headers
- Email threading (In-Reply-To, References)
- RFC 5322 compliant message formatting
- Connection reuse for sending multiple emails
Add lumenmail to your Gleam project:
gleam add lumenmailimport lumenmail/message
import lumenmail/smtp
pub fn main() {
// Build the email message
let email = message.new()
|> message.from_name_email("John Doe", "[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Hello from Gleam!")
|> message.text_body("This is a test email sent with lumenmail.")
// Connect to SMTP server and send
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("username", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_simple_email() {
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Hello!")
|> message.text_body("This is a plain text email.")
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("user", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_html_email() {
let email = message.new()
|> message.from_name_email("Newsletter", "[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Weekly Newsletter")
|> message.text_body("Your weekly update in plain text.")
|> message.html_body("<h1>Weekly Newsletter</h1><p>Your weekly update!</p>")
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("user", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_with_attachment() {
let pdf_data = <<...>> // Your PDF file as BitArray
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Document Attached")
|> message.text_body("Please find the document attached.")
|> message.attachment("document.pdf", message.ApplicationOctetStream, pdf_data)
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("user", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_to_multiple() {
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.to_name_email("Jane Doe", "[email protected]")
|> message.cc_email("[email protected]")
|> message.bcc_email("[email protected]")
|> message.subject("Team Update")
|> message.text_body("Hello team!")
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("user", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_via_gmail() {
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Sent from Gmail")
|> message.text_body("Hello from Gmail!")
// Gmail uses port 587 with STARTTLS
let assert Ok(client) = smtp.builder("smtp.gmail.com", 587)
|> smtp.auth("[email protected]", "your-app-password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_with_implicit_tls() {
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Secure Email")
|> message.text_body("Sent over implicit TLS.")
// Port 465 automatically uses implicit TLS
let assert Ok(client) = smtp.builder("smtp.example.com", 465)
|> smtp.auth("user", "password")
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
import lumenmail/types
pub fn send_with_oauth2() {
let email = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("OAuth2 Email")
|> message.text_body("Sent using OAuth2!")
let assert Ok(client) = smtp.builder("smtp.gmail.com", 587)
|> smtp.credentials(types.OAuth2("[email protected]", "oauth2-access-token"))
|> smtp.connect()
let assert Ok(_) = smtp.send(client, email)
let assert Ok(_) = smtp.close(client)
}import lumenmail/message
import lumenmail/smtp
pub fn send_multiple_emails() {
let assert Ok(client) = smtp.builder("smtp.example.com", 587)
|> smtp.auth("user", "password")
|> smtp.connect()
// Send first email
let email1 = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Email 1")
|> message.text_body("First email")
let assert Ok(_) = smtp.send(client, email1)
// Reset connection state
let assert Ok(_) = smtp.reset(client)
// Send second email
let email2 = message.new()
|> message.from_email("[email protected]")
|> message.to_email("[email protected]")
|> message.subject("Email 2")
|> message.text_body("Second email")
let assert Ok(_) = smtp.send(client, email2)
let assert Ok(_) = smtp.close(client)
}| Function | Description |
|---|---|
message.new() |
Create a new empty message |
message.from_email(msg, email) |
Set sender email |
message.from_name_email(msg, name, email) |
Set sender with display name |
message.to_email(msg, email) |
Add To recipient |
message.to_name_email(msg, name, email) |
Add To recipient with name |
message.cc_email(msg, email) |
Add CC recipient |
message.bcc_email(msg, email) |
Add BCC recipient |
message.subject(msg, subject) |
Set subject line |
message.text_body(msg, text) |
Set plain text body |
message.html_body(msg, html) |
Set HTML body |
message.attachment(msg, filename, content_type, data) |
Add file attachment |
message.inline_attachment(msg, filename, content_type, data, content_id) |
Add inline attachment |
message.header(msg, name, value) |
Add custom header |
message.priority(msg, priority) |
Set email priority |
message.reply_to(msg, address) |
Set Reply-To address |
| Function | Description |
|---|---|
smtp.builder(host, port) |
Create SMTP client builder |
smtp.auth(builder, username, password) |
Set authentication credentials |
smtp.credentials(builder, creds) |
Set credentials (Plain or OAuth2) |
smtp.implicit_tls(builder, enabled) |
Enable/disable implicit TLS |
smtp.timeout(builder, ms) |
Set connection timeout |
smtp.helo_host(builder, hostname) |
Set HELO hostname |
smtp.allow_invalid_certs(builder, allow) |
Allow invalid TLS certs (testing only) |
smtp.connect(builder) |
Connect to SMTP server |
| Function | Description |
|---|---|
smtp.send(client, message) |
Send an email message |
smtp.send_raw(client, from, to, data) |
Send raw email data |
smtp.reset(client) |
Reset connection for next email |
smtp.noop(client) |
Send NOOP to keep connection alive |
smtp.close(client) |
Close the connection |
smtp.capabilities(client) |
Get server capabilities |
| Port | Protocol | Description |
|---|---|---|
| 25 | SMTP | Standard SMTP (often blocked by ISPs) |
| 587 | Submission | SMTP with STARTTLS (recommended) |
| 465 | SMTPS | SMTP over implicit TLS |
gleam test # Run the tests
gleam build # Build the projectApache-2.0 OR MIT