diff --git a/Cargo.lock b/Cargo.lock
index 22d759f..95beaac 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -541,10 +541,12 @@ version = "0.10.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8033576bf9f051fce6cb92b6264114b4340896c352a9ff38b67bd4cde924635"
 dependencies = [
+ "async-trait",
  "base64 0.21.0",
  "email-encoding",
  "email_address",
  "fastrand",
+ "futures-io",
  "futures-util",
  "hostname",
  "httpdate",
@@ -557,6 +559,7 @@ dependencies = [
  "rustls-pemfile",
  "socket2",
  "tokio",
+ "tokio-rustls",
  "webpki-roots",
 ]
 
@@ -1087,6 +1090,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tokio-rustls"
+version = "0.23.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c43ee83903113e03984cb9e5cebe6c04a5116269e900e3ddba8f068a62adda59"
+dependencies = [
+ "rustls",
+ "tokio",
+ "webpki",
+]
+
 [[package]]
 name = "tokio-util"
 version = "0.7.7"
diff --git a/Cargo.toml b/Cargo.toml
index 4e3b5dd..de92207 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,7 +12,7 @@ askama = { git = "https://github.com/djc/askama.git" }
 askama_axum = { git = "https://github.com/djc/askama.git", package = "askama_axum" }
 axum = { version = "0.6", default-features = false, features = ["http1", "form", "tokio", "macros"] }
 captcha = { version = "0.0.9", default-features = false }
-lettre = { version = "0.10", default-features = false, features = ["smtp-transport", "hostname", "rustls-tls", "pool", "builder"] }
+lettre = { version = "0.10", default-features = false, features = ["smtp-transport", "hostname", "tokio1-rustls-tls", "pool", "builder"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_yaml = "0.9"
 time = "0.3"
diff --git a/src/mailer.rs b/src/mailer.rs
index 576ab1d..ecaa016 100644
--- a/src/mailer.rs
+++ b/src/mailer.rs
@@ -1,29 +1,39 @@
 use anyhow::{Context, Result};
 use lettre::{
-    message::{Mailbox, MessageBuilder},
-    transport::smtp::authentication::Credentials,
-    Message, SmtpTransport, Transport,
+    message::{Mailbox, Message, MessageBuilder},
+    transport::{
+        smtp::{authentication::Credentials, AsyncSmtpTransport},
+        AsyncTransport,
+    },
+    Tokio1Executor,
 };
 
 use crate::config::Config;
 
+type ASmtpTransport = AsyncSmtpTransport<Tokio1Executor>;
+
+/// Mail sender.
 pub struct Mailer {
-    mailer: SmtpTransport,
+    mailer: ASmtpTransport,
     message_builder: MessageBuilder,
 }
 
 impl Mailer {
+    /// Tries to initialize the mailer.
     pub fn build(config: &Config) -> Result<Self> {
-        let creds = Credentials::new(
+        // Mail server credentials for login.
+        let credentials = Credentials::new(
             config.email_server.email.clone(),
             config.email_server.password.clone(),
         );
 
-        let mailer = SmtpTransport::relay(&config.email_server.server_name)
+        // Establish the connection.
+        let mailer = ASmtpTransport::relay(&config.email_server.server_name)
             .context("Failed to connect to the email server!")?
-            .credentials(creds)
+            .credentials(credentials)
             .build();
 
+        // Set the From and To mailboxes for every sent mail.
         let message_builder = Message::builder()
             .from(
                 config
@@ -42,13 +52,19 @@ impl Mailer {
         })
     }
 
-    pub fn send(&self, name: &str, email: &str, telefon: &str, message: &str) -> Result<()> {
+    /// Sends a mail with data from the contact form.
+    pub async fn send(&self, name: &str, email: &str, telefon: &str, message: &str) -> Result<()> {
         let name = name.trim().to_string();
+        let subject = "Message from ".to_string() + &name;
+        let reply_to = Mailbox::new(
+            Some(name),
+            email
+                .parse()
+                .context("Failed to parse the email from the form to an address!")?,
+        );
+
         let telefon = telefon.trim();
         let message = message.trim().to_string();
-
-        let subject = "Message from ".to_string() + &name;
-
         let body = if !telefon.is_empty() {
             message + "\n\nTelefon: " + telefon
         } else {
@@ -58,17 +74,15 @@ impl Mailer {
         let email = self
             .message_builder
             .clone()
-            .reply_to(Mailbox::new(
-                Some(name),
-                email
-                    .parse()
-                    .context("Failed to parse the email from the form to an address!")?,
-            ))
+            .reply_to(reply_to)
             .subject(subject)
             .body(body)
             .context("Failed to build email!")?;
 
-        self.mailer.send(&email).context("Failed to send email!")?;
+        self.mailer
+            .send(email)
+            .await
+            .context("Failed to send email!")?;
 
         Ok(())
     }
diff --git a/src/routes.rs b/src/routes.rs
index e061f47..df077cc 100644
--- a/src/routes.rs
+++ b/src/routes.rs
@@ -112,7 +112,10 @@ pub async fn submit(
         .await;
     }
 
-    match mailer.send(&form.name, &form.email, &form.telefon, &form.message) {
+    match mailer
+        .send(&form.name, &form.email, &form.telefon, &form.message)
+        .await
+    {
         Ok(_) => (),
         Err(e) => {
             error!("{e:?}");