diff --git a/src/transport/stub/mod.rs b/src/transport/stub/mod.rs
index 7b0a13f..aa43e7c 100644
--- a/src/transport/stub/mod.rs
+++ b/src/transport/stub/mod.rs
@@ -1,10 +1,12 @@
-//! The stub transport only logs message envelope and drops the content. It can be useful for
-//! testing purposes.
+//! The stub transport logs message envelopes as well as contents. It can be useful for testing
+//! purposes.
 //!
-//! #### Stub Transport
+//! # Stub Transport
 //!
-//! The stub transport returns provided result and drops the content. It can be useful for
-//! testing purposes.
+//! The stub transport logs message envelopes as well as contents. It can be useful for testing
+//! purposes.
+//!
+//! # Examples
 //!
 //! ```rust
 //! # #[cfg(feature = "builder")]
@@ -12,7 +14,7 @@
 //! use lettre::{transport::stub::StubTransport, Message, Transport};
 //!
 //! # use std::error::Error;
-//! # fn main() -> Result<(), Box<dyn Error>> {
+//! # fn try_main() -> Result<(), Box<dyn Error>> {
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
@@ -23,15 +25,29 @@
 //! let mut sender = StubTransport::new_ok();
 //! let result = sender.send(&email);
 //! assert!(result.is_ok());
+//! assert_eq!(
+//!     sender.messages(),
+//!     vec![(
+//!         email.envelope().clone(),
+//!         String::from_utf8(email.formatted()).unwrap()
+//!     )],
+//! );
 //! # Ok(())
 //! # }
+//! # try_main().unwrap();
 //! # }
 //! ```
 
-use std::{error::Error as StdError, fmt};
+use std::{
+    error::Error as StdError,
+    fmt,
+    sync::{Arc, Mutex as StdMutex},
+};
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 use async_trait::async_trait;
+#[cfg(any(feature = "tokio1", feature = "async-std1"))]
+use futures_util::lock::Mutex as FuturesMutex;
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 use crate::AsyncTransport;
@@ -48,47 +64,113 @@ impl fmt::Display for Error {
 
 impl StdError for Error {}
 
-/// This transport logs the message envelope and returns the given response
-#[derive(Debug, Clone, Copy)]
+/// This transport logs messages and always returns the given response
+#[derive(Debug, Clone)]
 pub struct StubTransport {
     response: Result<(), Error>,
+    message_log: Arc<StdMutex<Vec<(Envelope, String)>>>,
+}
+
+/// This transport logs messages and always returns the given response
+#[derive(Debug, Clone)]
+#[cfg(any(feature = "tokio1", feature = "async-std1"))]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "tokio1", feature = "async-std1"))))]
+pub struct AsyncStubTransport {
+    response: Result<(), Error>,
+    message_log: Arc<FuturesMutex<Vec<(Envelope, String)>>>,
 }
 
 impl StubTransport {
     /// Creates a new transport that always returns the given Result
-    pub fn new(response: Result<(), Error>) -> StubTransport {
-        StubTransport { response }
+    pub fn new(response: Result<(), Error>) -> Self {
+        Self {
+            response,
+            message_log: Arc::new(StdMutex::new(vec![])),
+        }
     }
 
     /// Creates a new transport that always returns a success response
-    pub fn new_ok() -> StubTransport {
-        StubTransport { response: Ok(()) }
+    pub fn new_ok() -> Self {
+        Self {
+            response: Ok(()),
+            message_log: Arc::new(StdMutex::new(vec![])),
+        }
     }
 
     /// Creates a new transport that always returns an error
-    pub fn new_error() -> StubTransport {
-        StubTransport {
+    pub fn new_error() -> Self {
+        Self {
             response: Err(Error),
+            message_log: Arc::new(StdMutex::new(vec![])),
         }
     }
+
+    /// Return all logged messages sent using [`Transport::send_raw`]
+    pub fn messages(&self) -> Vec<(Envelope, String)> {
+        self.message_log
+            .lock()
+            .expect("Couldn't acquire lock to write message log")
+            .clone()
+    }
+}
+
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+impl AsyncStubTransport {
+    /// Creates a new transport that always returns the given Result
+    pub fn new(response: Result<(), Error>) -> Self {
+        Self {
+            response,
+            message_log: Arc::new(FuturesMutex::new(vec![])),
+        }
+    }
+
+    /// Creates a new transport that always returns a success response
+    pub fn new_ok() -> Self {
+        Self {
+            response: Ok(()),
+            message_log: Arc::new(FuturesMutex::new(vec![])),
+        }
+    }
+
+    /// Creates a new transport that always returns an error
+    pub fn new_error() -> Self {
+        Self {
+            response: Err(Error),
+            message_log: Arc::new(FuturesMutex::new(vec![])),
+        }
+    }
+
+    /// Return all logged messages sent using [`AsyncTransport::send_raw`]
+    #[cfg(any(feature = "tokio1", feature = "async-std1"))]
+    pub async fn messages(&self) -> Vec<(Envelope, String)> {
+        self.message_log.lock().await.clone()
+    }
 }
 
 impl Transport for StubTransport {
     type Ok = ();
     type Error = Error;
 
-    fn send_raw(&self, _envelope: &Envelope, _email: &[u8]) -> Result<Self::Ok, Self::Error> {
+    fn send_raw(&self, envelope: &Envelope, email: &[u8]) -> Result<Self::Ok, Self::Error> {
+        self.message_log
+            .lock()
+            .expect("Couldn't acquire lock to write message log")
+            .push((envelope.clone(), String::from_utf8_lossy(email).into()));
         self.response
     }
 }
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 #[async_trait]
-impl AsyncTransport for StubTransport {
+impl AsyncTransport for AsyncStubTransport {
     type Ok = ();
     type Error = Error;
 
-    async fn send_raw(&self, _envelope: &Envelope, _email: &[u8]) -> Result<Self::Ok, Self::Error> {
+    async fn send_raw(&self, envelope: &Envelope, email: &[u8]) -> Result<Self::Ok, Self::Error> {
+        self.message_log
+            .lock()
+            .await
+            .push((envelope.clone(), String::from_utf8_lossy(email).into()));
         self.response
     }
 }
diff --git a/tests/transport_stub.rs b/tests/transport_stub.rs
index 01b7119..321d1f3 100644
--- a/tests/transport_stub.rs
+++ b/tests/transport_stub.rs
@@ -17,19 +17,25 @@ mod sync {
 
         sender_ok.send(&email).unwrap();
         sender_ko.send(&email).unwrap_err();
+
+        let expected_messages = vec![(
+            email.envelope().clone(),
+            String::from_utf8(email.formatted()).unwrap(),
+        )];
+        assert_eq!(sender_ok.messages(), expected_messages);
     }
 }
 
 #[cfg(test)]
 #[cfg(all(feature = "builder", feature = "tokio1"))]
 mod tokio_1 {
-    use lettre::{transport::stub::StubTransport, AsyncTransport, Message};
+    use lettre::{transport::stub::AsyncStubTransport, AsyncTransport, Message};
     use tokio1_crate as tokio;
 
     #[tokio::test]
     async fn stub_transport_tokio1() {
-        let sender_ok = StubTransport::new_ok();
-        let sender_ko = StubTransport::new_error();
+        let sender_ok = AsyncStubTransport::new_ok();
+        let sender_ko = AsyncStubTransport::new_error();
         let email = Message::builder()
             .from("NoBody <nobody@domain.tld>".parse().unwrap())
             .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
@@ -39,19 +45,25 @@ mod tokio_1 {
             .unwrap();
 
         sender_ok.send(email.clone()).await.unwrap();
-        sender_ko.send(email).await.unwrap_err();
+        sender_ko.send(email.clone()).await.unwrap_err();
+
+        let expected_messages = vec![(
+            email.envelope().clone(),
+            String::from_utf8(email.formatted()).unwrap(),
+        )];
+        assert_eq!(sender_ok.messages().await, expected_messages);
     }
 }
 
 #[cfg(test)]
 #[cfg(all(feature = "builder", feature = "async-std1"))]
 mod asyncstd_1 {
-    use lettre::{transport::stub::StubTransport, AsyncTransport, Message};
+    use lettre::{transport::stub::AsyncStubTransport, AsyncTransport, Message};
 
     #[async_std::test]
     async fn stub_transport_asyncstd1() {
-        let sender_ok = StubTransport::new_ok();
-        let sender_ko = StubTransport::new_error();
+        let sender_ok = AsyncStubTransport::new_ok();
+        let sender_ko = AsyncStubTransport::new_error();
         let email = Message::builder()
             .from("NoBody <nobody@domain.tld>".parse().unwrap())
             .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
@@ -61,6 +73,12 @@ mod asyncstd_1 {
             .unwrap();
 
         sender_ok.send(email.clone()).await.unwrap();
-        sender_ko.send(email).await.unwrap_err();
+        sender_ko.send(email.clone()).await.unwrap_err();
+
+        let expected_messages = vec![(
+            email.envelope().clone(),
+            String::from_utf8(email.formatted()).unwrap(),
+        )];
+        assert_eq!(sender_ok.messages().await, expected_messages);
     }
 }