Use connection url to configure email (fixes #5472) (#5476)

* Use connection url for configure email (fixes #5472)

* clippy

config/defaults.hjson

@@ -70,16 +70,10 @@
   }
   # Email sending configuration. All options except login/password are mandatory
   email: {
-    # Hostname and port of the smtp server
-    smtp_server: "localhost:25"
-    # Login name for smtp server
-    smtp_login: "string"
-    # Password to login to the smtp server
-    smtp_password: "string"
+    # https://docs.rs/lettre/0.11.14/lettre/transport/smtp/struct.AsyncSmtpTransport.html#method.from_url
+    connection: "smtps://user:pass@hostname:port"
     # Address to send emails from, eg "noreply@your-instance.com"
     smtp_from_address: "noreply@example.com"
-    # Whether or not smtp connections should use tls. Can be none, tls, or starttls
-    tls_type: "none"
   }
   # Parameters for automatic configuration of new instance (only used at first start)
   setup: {

crates/utils/Cargo.toml

@@ -79,6 +79,7 @@ lettre = { version = "0.11.12", default-features = false, features = [
   "builder",
   "smtp-transport",
   "tokio1-rustls-tls",
+  "pool",
 ], optional = true }
 markdown-it = { version = "0.6.1", optional = true }
 ts-rs = { workspace = true, optional = true }

crates/utils/src/email.rs

@@ -5,13 +5,13 @@ use crate::{
 use html2text;
 use lettre::{
   message::{Mailbox, MultiPart},
-  transport::smtp::{authentication::Credentials, extension::ClientId},
+  transport::smtp::extension::ClientId,
   Address,
   AsyncTransport,
   Message,
 };
 use rosetta_i18n::{Language, LanguageId};
-use std::str::FromStr;
+use std::{str::FromStr, sync::OnceLock};
 use translations::Lang;
 use uuid::Uuid;
 
@@ -28,21 +28,16 @@ pub async fn send_email(
   html: &str,
   settings: &Settings,
 ) -> LemmyResult<()> {
+  static MAILER: OnceLock<AsyncSmtpTransport> = OnceLock::new();
   let email_config = settings.email.clone().ok_or(LemmyErrorType::NoEmailSetup)?;
-  let domain = settings.hostname.clone();
 
-  let (smtp_server, smtp_port) = {
-    let email_and_port = email_config.smtp_server.split(':').collect::<Vec<&str>>();
-    let email = *email_and_port
-      .first()
-      .ok_or(LemmyErrorType::EmailRequired)?;
-    let port = email_and_port
-      .get(1)
-      .ok_or(LemmyErrorType::EmailSmtpServerNeedsAPort)?
-      .parse::<u16>()?;
-
-    (email, port)
-  };
+  #[expect(clippy::expect_used)]
+  let mailer = MAILER.get_or_init(|| {
+    AsyncSmtpTransport::from_url(&email_config.connection)
+      .expect("init email transport")
+      .hello_name(ClientId::Domain(settings.hostname.clone()))
+      .build()
+  });
 
   // use usize::MAX as the line wrap length, since lettre handles the wrapping for us
   let plain_text = html2text::from_read(html.as_bytes(), usize::MAX)?;
@@ -70,24 +65,6 @@ pub async fn send_email(
     ))
     .with_lemmy_type(LemmyErrorType::EmailSendFailed)?;
 
-  // don't worry about 'dangeous'. it's just that leaving it at the default configuration
-  // is bad.
-
-  // Set the TLS
-  let mut builder = match email_config.tls_type.as_str() {
-    "starttls" => AsyncSmtpTransport::starttls_relay(smtp_server)?.port(smtp_port),
-    "tls" => AsyncSmtpTransport::relay(smtp_server)?.port(smtp_port),
-    _ => AsyncSmtpTransport::builder_dangerous(smtp_server).port(smtp_port),
-  };
-
-  // Set the creds if they exist
-  let smtp_password = email_config.smtp_password();
-  if let (Some(username), Some(password)) = (email_config.smtp_login, smtp_password) {
-    builder = builder.credentials(Credentials::new(username, password));
-  }
-
-  let mailer = builder.hello_name(ClientId::Domain(domain)).build();
-
   mailer
     .send(email)
     .await

crates/utils/src/error.rs

@@ -74,7 +74,6 @@ pub enum LemmyErrorType {
   ObjectNotLocal,
   NoEmailSetup,
   LocalSiteNotSetup,
-  EmailSmtpServerNeedsAPort,
   InvalidEmailAddress(String),
   RateLimitError,
   InvalidName,

crates/utils/src/settings/structs.rs

@@ -156,28 +156,13 @@ pub struct DatabaseConfig {
 #[derive(Debug, Deserialize, Serialize, Clone, Document, SmartDefault)]
 #[serde(default, deny_unknown_fields)]
 pub struct EmailConfig {
-  /// Hostname and port of the smtp server
-  #[doku(example = "localhost:25")]
-  pub smtp_server: String,
-  /// Login name for smtp server
-  pub smtp_login: Option<String>,
-  /// Password to login to the smtp server
-  smtp_password: Option<String>,
-  #[doku(example = "noreply@example.com")]
+  /// https://docs.rs/lettre/0.11.14/lettre/transport/smtp/struct.AsyncSmtpTransport.html#method.from_url
+  #[default("smtp://localhost:25")]
+  #[doku(example = "smtps://user:pass@hostname:port")]
+  pub(crate) connection: String,
   /// Address to send emails from, eg "noreply@your-instance.com"
-  pub smtp_from_address: String,
-  /// Whether or not smtp connections should use tls. Can be none, tls, or starttls
-  #[default("none")]
-  #[doku(example = "none")]
-  pub tls_type: String,
-}
-
-impl EmailConfig {
-  pub fn smtp_password(&self) -> Option<String> {
-    std::env::var("LEMMY_SMTP_PASSWORD")
-      .ok()
-      .or(self.smtp_password.clone())
-  }
+  #[doku(example = "noreply@example.com")]
+  pub(crate) smtp_from_address: String,
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone, Default, Document)]