diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 2aaa531..4324eb3 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ env:
 
 jobs:
   rustfmt:
-    name: rustfmt / stable
+    name: rustfmt / nightly-2022-02-11
     runs-on: ubuntu-latest
 
     steps:
@@ -22,7 +22,7 @@ jobs:
 
       - name: Install rust
         run: |
-          rustup update --no-self-update stable
+          rustup default nightly-2022-02-11
           rustup component add rustfmt
 
       - name: cargo fmt
diff --git a/examples/tokio1_smtp_starttls.rs b/examples/tokio1_smtp_starttls.rs
index 81b2c21..19431d5 100644
--- a/examples/tokio1_smtp_starttls.rs
+++ b/examples/tokio1_smtp_starttls.rs
@@ -1,12 +1,11 @@
 // This line is only to make it compile from lettre's examples folder,
 // since it uses Rust 2018 crate renaming to import tokio.
 // Won't be needed in user's code.
-use tokio1_crate as tokio;
-
 use lettre::{
     transport::smtp::authentication::Credentials, AsyncSmtpTransport, AsyncTransport, Message,
     Tokio1Executor,
 };
+use tokio1_crate as tokio;
 
 #[tokio::main]
 async fn main() {
diff --git a/examples/tokio1_smtp_tls.rs b/examples/tokio1_smtp_tls.rs
index 564d087..5c86953 100644
--- a/examples/tokio1_smtp_tls.rs
+++ b/examples/tokio1_smtp_tls.rs
@@ -1,12 +1,11 @@
 // This line is only to make it compile from lettre's examples folder,
 // since it uses Rust 2018 crate renaming to import tokio.
 // Won't be needed in user's code.
-use tokio1_crate as tokio;
-
 use lettre::{
     transport::smtp::authentication::Credentials, AsyncSmtpTransport, AsyncTransport, Message,
     Tokio1Executor,
 };
+use tokio1_crate as tokio;
 
 #[tokio::main]
 async fn main() {
diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 0000000..cc7e7de
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,3 @@
+format_code_in_doc_comments = true
+imports_granularity = "Crate"
+group_imports = "StdExternalCrate"
diff --git a/src/address/types.rs b/src/address/types.rs
index 3006388..36c9d4a 100644
--- a/src/address/types.rs
+++ b/src/address/types.rs
@@ -1,8 +1,5 @@
 //! Representation of an email address
 
-use idna::domain_to_ascii;
-use once_cell::sync::Lazy;
-use regex::Regex;
 use std::{
     convert::{TryFrom, TryInto},
     error::Error,
@@ -12,6 +9,10 @@ use std::{
     str::FromStr,
 };
 
+use idna::domain_to_ascii;
+use once_cell::sync::Lazy;
+use regex::Regex;
+
 /// Represents an email address with a user and a domain name.
 ///
 /// This type contains email in canonical form (_user@domain.tld_).
diff --git a/src/executor.rs b/src/executor.rs
index be00192..672503e 100644
--- a/src/executor.rs
+++ b/src/executor.rs
@@ -1,7 +1,3 @@
-use async_trait::async_trait;
-#[cfg(all(feature = "smtp-transport", feature = "async-std1"))]
-use futures_util::future::BoxFuture;
-
 use std::fmt::Debug;
 #[cfg(feature = "smtp-transport")]
 use std::future::Future;
@@ -12,6 +8,10 @@ use std::path::Path;
 #[cfg(feature = "smtp-transport")]
 use std::time::Duration;
 
+use async_trait::async_trait;
+#[cfg(all(feature = "smtp-transport", feature = "async-std1"))]
+use futures_util::future::BoxFuture;
+
 #[cfg(all(
     feature = "smtp-transport",
     any(feature = "tokio1", feature = "async-std1")
diff --git a/src/lib.rs b/src/lib.rs
index 0fa1d3b..d5223df 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -175,6 +175,8 @@ mod executor;
 pub mod message;
 pub mod transport;
 
+use std::error::Error as StdError;
+
 #[cfg(feature = "async-std1")]
 pub use self::executor::AsyncStd1Executor;
 #[cfg(all(any(feature = "tokio1", feature = "async-std1")))]
@@ -211,14 +213,12 @@ pub use crate::transport::sendmail::SendmailTransport;
     any(feature = "tokio1", feature = "async-std1")
 ))]
 pub use crate::transport::smtp::AsyncSmtpTransport;
+#[cfg(feature = "smtp-transport")]
+pub use crate::transport::smtp::SmtpTransport;
 #[doc(inline)]
 pub use crate::transport::Transport;
 use crate::{address::Envelope, error::Error};
 
-#[cfg(feature = "smtp-transport")]
-pub use crate::transport::smtp::SmtpTransport;
-use std::error::Error as StdError;
-
 pub(crate) type BoxError = Box<dyn StdError + Send + Sync>;
 
 #[cfg(test)]
diff --git a/src/message/attachment.rs b/src/message/attachment.rs
index ddd62a1..f6d25a6 100644
--- a/src/message/attachment.rs
+++ b/src/message/attachment.rs
@@ -29,7 +29,7 @@ impl Attachment {
     /// # use std::error::Error;
     /// use std::fs;
     ///
-    /// use lettre::message::{Attachment, header::ContentType};
+    /// use lettre::message::{header::ContentType, Attachment};
     ///
     /// # fn main() -> Result<(), Box<dyn Error>> {
     /// let filename = String::from("invoice.pdf");
@@ -64,7 +64,7 @@ impl Attachment {
     /// # use std::error::Error;
     /// use std::fs;
     ///
-    /// use lettre::message::{Attachment, header::ContentType};
+    /// use lettre::message::{header::ContentType, Attachment};
     ///
     /// # fn main() -> Result<(), Box<dyn Error>> {
     /// let content_id = String::from("123");
diff --git a/src/message/dkim.rs b/src/message/dkim.rs
index edb9411..3cae12c 100644
--- a/src/message/dkim.rs
+++ b/src/message/dkim.rs
@@ -1,17 +1,21 @@
-use crate::message::{
-    header::{HeaderName, HeaderValue},
-    Headers, Message,
+use std::{
+    borrow::Cow,
+    error::Error as StdError,
+    fmt::{self, Display, Write},
+    iter::IntoIterator,
+    time::SystemTime,
 };
+
 use ed25519_dalek::Signer;
 use once_cell::sync::Lazy;
 use regex::{bytes::Regex as BRegex, Regex};
 use rsa::{pkcs1::FromRsaPrivateKey, Hash, PaddingScheme, RsaPrivateKey};
 use sha2::{Digest, Sha256};
-use std::borrow::Cow;
-use std::error::Error as StdError;
-use std::fmt::{self, Display, Write};
-use std::iter::IntoIterator;
-use std::time::SystemTime;
+
+use crate::message::{
+    header::{HeaderName, HeaderValue},
+    Headers, Message,
+};
 
 /// Describe Dkim Canonicalization to apply to either body or headers
 #[derive(Copy, Clone, Debug)]
@@ -381,15 +385,20 @@ pub(super) fn dkim_sign(message: &mut Message, dkim_config: &DkimConfig) {
 
 #[cfg(test)]
 mod test {
+    use std::{
+        io::Write,
+        process::{Command, Stdio},
+    };
+
     use super::{
-        super::header::{HeaderName, HeaderValue},
-        super::{Header, Message},
+        super::{
+            header::{HeaderName, HeaderValue},
+            Header, Message,
+        },
         dkim_canonicalize_body, dkim_canonicalize_header_value, dkim_canonicalize_headers,
         DkimCanonicalizationType, DkimConfig, DkimSigningAlgorithm, DkimSigningKey,
     };
     use crate::StdError;
-    use std::io::Write;
-    use std::process::{Command, Stdio};
 
     #[derive(Clone)]
     struct TestHeader(String);
diff --git a/src/message/header/content_type.rs b/src/message/header/content_type.rs
index c57de25..5a588db 100644
--- a/src/message/header/content_type.rs
+++ b/src/message/header/content_type.rs
@@ -94,11 +94,13 @@ impl Display for ContentTypeErr {
 // -- Serialization and Deserialization --
 #[cfg(feature = "serde")]
 mod serde {
-    use serde::de::{self, Deserialize, Deserializer, Visitor};
-    use serde::ser::{Serialize, Serializer};
-
     use std::fmt;
 
+    use serde::{
+        de::{self, Deserialize, Deserializer, Visitor},
+        ser::{Serialize, Serializer},
+    };
+
     use super::ContentType;
 
     impl Serialize for ContentType {
diff --git a/src/message/mailbox/serde.rs b/src/message/mailbox/serde.rs
index 5ab61ff..64868c3 100644
--- a/src/message/mailbox/serde.rs
+++ b/src/message/mailbox/serde.rs
@@ -1,10 +1,12 @@
-use crate::message::{Mailbox, Mailboxes};
+use std::fmt::{Formatter, Result as FmtResult};
+
 use serde::{
     de::{Deserializer, Error as DeError, MapAccess, SeqAccess, Visitor},
     ser::Serializer,
     Deserialize, Serialize,
 };
-use std::fmt::{Formatter, Result as FmtResult};
+
+use crate::message::{Mailbox, Mailboxes};
 
 impl Serialize for Mailbox {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -152,9 +154,10 @@ impl<'de> Deserialize<'de> for Mailboxes {
 
 #[cfg(test)]
 mod test {
+    use serde_json::from_str;
+
     use super::*;
     use crate::address::Address;
-    use serde_json::from_str;
 
     #[test]
     fn parse_address_string() {
diff --git a/src/message/mailbox/types.rs b/src/message/mailbox/types.rs
index 939fd45..74b4acb 100644
--- a/src/message/mailbox/types.rs
+++ b/src/message/mailbox/types.rs
@@ -1,4 +1,3 @@
-use crate::address::{Address, AddressError};
 use std::{
     convert::TryFrom,
     fmt::{Display, Formatter, Result as FmtResult, Write},
@@ -6,6 +5,8 @@ use std::{
     str::FromStr,
 };
 
+use crate::address::{Address, AddressError};
+
 /// Represents an email address with an optional name for the sender/recipient.
 ///
 /// This type contains email address and the sender/recipient name (_Some Name \<user@domain.tld\>_ or _withoutname@domain.tld_).
@@ -410,9 +411,10 @@ fn write_quoted_string_char(f: &mut Formatter<'_>, c: u8) -> FmtResult {
 
 #[cfg(test)]
 mod test {
-    use super::Mailbox;
     use std::convert::TryInto;
 
+    use super::Mailbox;
+
     #[test]
     fn mailbox_format_address_only() {
         assert_eq!(
diff --git a/src/message/mimebody.rs b/src/message/mimebody.rs
index b9e22ca..3ab5620 100644
--- a/src/message/mimebody.rs
+++ b/src/message/mimebody.rs
@@ -1,11 +1,11 @@
-use std::io::Write;
+use std::{io::Write, iter::repeat_with};
+
+use mime::Mime;
 
 use crate::message::{
     header::{self, ContentTransferEncoding, ContentType, Header, Headers},
     EmailFormat, IntoBody,
 };
-use mime::Mime;
-use std::iter::repeat_with;
 
 /// MIME part variants
 #[derive(Debug, Clone)]
diff --git a/src/message/mod.rs b/src/message/mod.rs
index 4a5e3da..6608abf 100644
--- a/src/message/mod.rs
+++ b/src/message/mod.rs
@@ -106,9 +106,10 @@
 //!
 //! ```rust
 //! # use std::error::Error;
-//! use lettre::message::{header, Attachment, Body, Message, MultiPart, SinglePart};
 //! use std::fs;
 //!
+//! use lettre::message::{header, Attachment, Body, Message, MultiPart, SinglePart};
+//!
 //! # fn main() -> Result<(), Box<dyn Error>> {
 //! let image = fs::read("docs/lettre.png")?;
 //! // this image_body can be cloned and reused between emails.
@@ -510,16 +511,18 @@ impl Message {
     ///
     /// Example:
     /// ```rust
-    /// use lettre::Message;
-    /// use lettre::message::dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey};
+    /// use lettre::{
+    ///     message::dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey},
+    ///     Message,
+    /// };
     ///
     /// let mut message = Message::builder()
-    /// .from("Alice <alice@example.org>".parse().unwrap())
-    /// .reply_to("Bob <bob@example.org>".parse().unwrap())
-    /// .to("Carla <carla@example.net>".parse().unwrap())
-    /// .subject("Hello")
-    /// .body("Hi there, it's a test email, with utf-8 chars ë!\n\n\n".to_string())
-    /// .unwrap();
+    ///     .from("Alice <alice@example.org>".parse().unwrap())
+    ///     .reply_to("Bob <bob@example.org>".parse().unwrap())
+    ///     .to("Carla <carla@example.net>".parse().unwrap())
+    ///     .subject("Hello")
+    ///     .body("Hi there, it's a test email, with utf-8 chars ë!\n\n\n".to_string())
+    ///     .unwrap();
     /// let key = "-----BEGIN RSA PRIVATE KEY-----
     /// MIIEowIBAAKCAQEAt2gawjoybf0mAz0mSX0cq1ah5F9cPazZdCwLnFBhRufxaZB8
     /// NLTdc9xfPIOK8l/xGrN7Nd63J4cTATqZukumczkA46O8YKHwa53pNT6NYwCNtDUL
@@ -548,8 +551,15 @@ impl Message {
     /// I45fbR4l+3D/30WMfZlM6bzZbwPXEnr2s1mirmuQpjumY9wLhK25
     /// -----END RSA PRIVATE KEY-----";
     /// let signing_key = DkimSigningKey::new(key.to_string(), DkimSigningAlgorithm::Rsa).unwrap();
-    /// message.sign(&DkimConfig::default_config("dkimtest".to_string(),"example.org".to_string(),signing_key));
-    /// println!("message: {}", std::str::from_utf8(&message.formatted()).unwrap());
+    /// message.sign(&DkimConfig::default_config(
+    ///     "dkimtest".to_string(),
+    ///     "example.org".to_string(),
+    ///     signing_key,
+    /// ));
+    /// println!(
+    ///     "message: {}",
+    ///     std::str::from_utf8(&message.formatted()).unwrap()
+    /// );
     /// ```
     #[cfg(feature = "dkim")]
     pub fn sign(&mut self, dkim_config: &DkimConfig) {
diff --git a/src/transport/file/error.rs b/src/transport/file/error.rs
index cd84e9e..bbc6f0c 100644
--- a/src/transport/file/error.rs
+++ b/src/transport/file/error.rs
@@ -1,8 +1,9 @@
 //! Error and result type for file transport
 
-use crate::BoxError;
 use std::{error::Error as StdError, fmt};
 
+use crate::BoxError;
+
 /// The Errors that may occur when sending an email over SMTP
 pub struct Error {
     inner: Box<Inner>,
diff --git a/src/transport/file/mod.rs b/src/transport/file/mod.rs
index ef73522..27db775 100644
--- a/src/transport/file/mod.rs
+++ b/src/transport/file/mod.rs
@@ -9,9 +9,10 @@
 //! #
 //! # #[cfg(all(feature = "file-transport", feature = "builder"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{FileTransport, Message, Transport};
 //! use std::env::temp_dir;
 //!
+//! use lettre::{FileTransport, Message, Transport};
+//!
 //! // Write to the local temp directory
 //! let sender = FileTransport::new(temp_dir());
 //! let email = Message::builder()
@@ -41,9 +42,10 @@
 //! #
 //! # #[cfg(all(feature = "file-transport-envelope", feature = "builder"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{FileTransport, Message, Transport};
 //! use std::env::temp_dir;
 //!
+//! use lettre::{FileTransport, Message, Transport};
+//!
 //! // Write to the local temp directory
 //! let sender = FileTransport::with_envelope(temp_dir());
 //! let email = Message::builder()
@@ -70,7 +72,8 @@
 //! # #[cfg(all(feature = "tokio1", feature = "file-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
-//! use lettre::{AsyncTransport, Tokio1Executor, Message, AsyncFileTransport};
+//!
+//! use lettre::{AsyncFileTransport, AsyncTransport, Message, Tokio1Executor};
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<Tokio1Executor>::new(temp_dir());
@@ -95,7 +98,8 @@
 //! # #[cfg(all(feature = "async-std1", feature = "file-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
-//! use lettre::{AsyncTransport, AsyncStd1Executor, Message, AsyncFileTransport};
+//!
+//! use lettre::{AsyncFileTransport, AsyncStd1Executor, AsyncTransport, Message};
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<AsyncStd1Executor>::new(temp_dir());
@@ -132,20 +136,22 @@
 //! {"forward_path":["hei@domain.tld"],"reverse_path":"nobody@domain.tld"}
 //! ```
 
-pub use self::error::Error;
-use crate::{address::Envelope, Transport};
-#[cfg(any(feature = "async-std1", feature = "tokio1"))]
-use crate::{AsyncTransport, Executor};
-#[cfg(any(feature = "async-std1", feature = "tokio1"))]
-use async_trait::async_trait;
 #[cfg(any(feature = "async-std1", feature = "tokio1"))]
 use std::marker::PhantomData;
 use std::{
     path::{Path, PathBuf},
     str,
 };
+
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+use async_trait::async_trait;
 use uuid::Uuid;
 
+pub use self::error::Error;
+use crate::{address::Envelope, Transport};
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+use crate::{AsyncTransport, Executor};
+
 mod error;
 
 type Id = String;
diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index cb27a4d..9cde231 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -56,8 +56,7 @@
 //! #
 //! # #[cfg(all(feature = "builder", feature = "smtp-transport"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::transport::smtp::authentication::Credentials;
-//! use lettre::{Message, SmtpTransport, Transport};
+//! use lettre::{transport::smtp::authentication::Credentials, Message, SmtpTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
diff --git a/src/transport/sendmail/error.rs b/src/transport/sendmail/error.rs
index a2d80ee..ea613df 100644
--- a/src/transport/sendmail/error.rs
+++ b/src/transport/sendmail/error.rs
@@ -1,8 +1,9 @@
 //! Error and result type for sendmail transport
 
-use crate::BoxError;
 use std::{error::Error as StdError, fmt};
 
+use crate::BoxError;
+
 /// The Errors that may occur when sending an email over sendmail
 pub struct Error {
     inner: Box<Inner>,
diff --git a/src/transport/sendmail/mod.rs b/src/transport/sendmail/mod.rs
index 1c35b35..7916b52 100644
--- a/src/transport/sendmail/mod.rs
+++ b/src/transport/sendmail/mod.rs
@@ -33,7 +33,9 @@
 //! #
 //! # #[cfg(all(feature = "tokio1", feature = "sendmail-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
-//! use lettre::{Message, AsyncTransport, Tokio1Executor, AsyncSendmailTransport, SendmailTransport};
+//! use lettre::{
+//!     AsyncSendmailTransport, AsyncTransport, Message, SendmailTransport, Tokio1Executor,
+//! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
@@ -72,6 +74,17 @@
 //! # }
 //! ```
 
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+use std::marker::PhantomData;
+use std::{
+    ffi::OsString,
+    io::Write,
+    process::{Command, Stdio},
+};
+
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+use async_trait::async_trait;
+
 pub use self::error::Error;
 #[cfg(feature = "async-std1")]
 use crate::AsyncStd1Executor;
@@ -80,15 +93,6 @@ use crate::Tokio1Executor;
 use crate::{address::Envelope, Transport};
 #[cfg(any(feature = "async-std1", feature = "tokio1"))]
 use crate::{AsyncTransport, Executor};
-#[cfg(any(feature = "async-std1", feature = "tokio1"))]
-use async_trait::async_trait;
-#[cfg(any(feature = "async-std1", feature = "tokio1"))]
-use std::marker::PhantomData;
-use std::{
-    ffi::OsString,
-    io::Write,
-    process::{Command, Stdio},
-};
 
 mod error;
 
diff --git a/src/transport/smtp/authentication.rs b/src/transport/smtp/authentication.rs
index 0a3799b..63967e1 100644
--- a/src/transport/smtp/authentication.rs
+++ b/src/transport/smtp/authentication.rs
@@ -1,8 +1,9 @@
 //! Provides limited SASL authentication mechanisms
 
-use crate::transport::smtp::error::{self, Error};
 use std::fmt::{self, Debug, Display, Formatter};
 
+use crate::transport::smtp::error::{self, Error};
+
 /// Accepted authentication mechanisms
 ///
 /// Trying LOGIN last as it is deprecated.
diff --git a/src/transport/smtp/client/async_connection.rs b/src/transport/smtp/client/async_connection.rs
index 45bb1e3..b3cd03b 100644
--- a/src/transport/smtp/client/async_connection.rs
+++ b/src/transport/smtp/client/async_connection.rs
@@ -1,3 +1,9 @@
+use std::{fmt::Display, time::Duration};
+
+use futures_util::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+
+#[cfg(feature = "tracing")]
+use super::escape_crlf;
 use super::{AsyncNetworkStream, ClientCodec, TlsParameters};
 use crate::{
     transport::smtp::{
@@ -10,11 +16,6 @@ use crate::{
     },
     Envelope,
 };
-use futures_util::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
-use std::{fmt::Display, time::Duration};
-
-#[cfg(feature = "tracing")]
-use super::escape_crlf;
 
 macro_rules! try_smtp (
     ($err: expr, $client: ident) => ({
diff --git a/src/transport/smtp/client/async_net.rs b/src/transport/smtp/client/async_net.rs
index 1c1f3c6..bf4e201 100644
--- a/src/transport/smtp/client/async_net.rs
+++ b/src/transport/smtp/client/async_net.rs
@@ -6,25 +6,22 @@ use std::{
     time::Duration,
 };
 
+#[cfg(feature = "async-std1-native-tls")]
+use async_native_tls::TlsStream as AsyncStd1TlsStream;
+#[cfg(feature = "async-std1")]
+use async_std::net::{TcpStream as AsyncStd1TcpStream, ToSocketAddrs as AsyncStd1ToSocketAddrs};
 use futures_io::{
     AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, Error as IoError, ErrorKind,
     Result as IoResult,
 };
-#[cfg(feature = "tokio1")]
-use tokio1_crate::io::{AsyncRead as _, AsyncWrite as _, ReadBuf as Tokio1ReadBuf};
-
-#[cfg(feature = "async-std1")]
-use async_std::net::{TcpStream as AsyncStd1TcpStream, ToSocketAddrs as AsyncStd1ToSocketAddrs};
-#[cfg(feature = "tokio1")]
-use tokio1_crate::net::{TcpStream as Tokio1TcpStream, ToSocketAddrs as Tokio1ToSocketAddrs};
-
-#[cfg(feature = "async-std1-native-tls")]
-use async_native_tls::TlsStream as AsyncStd1TlsStream;
-#[cfg(feature = "tokio1-native-tls")]
-use tokio1_native_tls_crate::TlsStream as Tokio1TlsStream;
-
 #[cfg(feature = "async-std1-rustls-tls")]
 use futures_rustls::client::TlsStream as AsyncStd1RustlsTlsStream;
+#[cfg(feature = "tokio1")]
+use tokio1_crate::io::{AsyncRead as _, AsyncWrite as _, ReadBuf as Tokio1ReadBuf};
+#[cfg(feature = "tokio1")]
+use tokio1_crate::net::{TcpStream as Tokio1TcpStream, ToSocketAddrs as Tokio1ToSocketAddrs};
+#[cfg(feature = "tokio1-native-tls")]
+use tokio1_native_tls_crate::TlsStream as Tokio1TlsStream;
 #[cfg(feature = "tokio1-rustls-tls")]
 use tokio1_rustls::client::TlsStream as Tokio1RustlsTlsStream;
 
diff --git a/src/transport/smtp/client/connection.rs b/src/transport/smtp/client/connection.rs
index 2e36a0f..45e1b73 100644
--- a/src/transport/smtp/client/connection.rs
+++ b/src/transport/smtp/client/connection.rs
@@ -5,6 +5,8 @@ use std::{
     time::Duration,
 };
 
+#[cfg(feature = "tracing")]
+use super::escape_crlf;
 use super::{ClientCodec, NetworkStream, TlsParameters};
 use crate::{
     address::Envelope,
@@ -18,9 +20,6 @@ use crate::{
     },
 };
 
-#[cfg(feature = "tracing")]
-use super::escape_crlf;
-
 macro_rules! try_smtp (
     ($err: expr, $client: ident) => ({
         match $err {
diff --git a/src/transport/smtp/client/mod.rs b/src/transport/smtp/client/mod.rs
index 71fb3ae..68b750f 100644
--- a/src/transport/smtp/client/mod.rs
+++ b/src/transport/smtp/client/mod.rs
@@ -7,16 +7,14 @@
 //!
 //! # #[cfg(feature = "smtp-transport")]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::transport::smtp::{SMTP_PORT, extension::ClientId, commands::*, client::SmtpConnection};
+//! use lettre::transport::smtp::{
+//!     client::SmtpConnection, commands::*, extension::ClientId, SMTP_PORT,
+//! };
 //!
 //! let hello = ClientId::Domain("my_hostname".to_string());
 //! let mut client = SmtpConnection::connect(&("localhost", SMTP_PORT), None, &hello, None)?;
-//! client.command(
-//!         Mail::new(Some("user@example.com".parse()?), vec![])
-//!     )?;
-//! client.command(
-//!         Rcpt::new("user@example.org".parse()?, vec![])
-//!       )?;
+//! client.command(Mail::new(Some("user@example.com".parse()?), vec![]))?;
+//! client.command(Rcpt::new("user@example.org".parse()?, vec![]))?;
 //! client.command(Data)?;
 //! client.message("Test email".as_bytes())?;
 //! client.command(Quit)?;
diff --git a/src/transport/smtp/client/net.rs b/src/transport/smtp/client/net.rs
index b03863c..d6bed0e 100644
--- a/src/transport/smtp/client/net.rs
+++ b/src/transport/smtp/client/net.rs
@@ -9,7 +9,6 @@ use std::{
 
 #[cfg(feature = "native-tls")]
 use native_tls::TlsStream;
-
 #[cfg(feature = "rustls-tls")]
 use rustls::{ClientConnection, ServerName, StreamOwned};
 
diff --git a/src/transport/smtp/client/tls.rs b/src/transport/smtp/client/tls.rs
index 4777808..0b33f4f 100644
--- a/src/transport/smtp/client/tls.rs
+++ b/src/transport/smtp/client/tls.rs
@@ -1,5 +1,7 @@
-#[cfg(any(feature = "native-tls", feature = "rustls-tls"))]
-use crate::transport::smtp::{error, Error};
+use std::fmt::{self, Debug};
+#[cfg(feature = "rustls-tls")]
+use std::{sync::Arc, time::SystemTime};
+
 #[cfg(feature = "native-tls")]
 use native_tls::{Protocol, TlsConnector};
 #[cfg(feature = "rustls-tls")]
@@ -7,9 +9,9 @@ use rustls::{
     client::{ServerCertVerified, ServerCertVerifier, WebPkiVerifier},
     ClientConfig, Error as TlsError, OwnedTrustAnchor, RootCertStore, ServerName,
 };
-use std::fmt::{self, Debug};
-#[cfg(feature = "rustls-tls")]
-use std::{sync::Arc, time::SystemTime};
+
+#[cfg(any(feature = "native-tls", feature = "rustls-tls"))]
+use crate::transport::smtp::{error, Error};
 
 /// Accepted protocols by default.
 /// This removes TLS 1.0 and 1.1 compared to tls-native defaults.
diff --git a/src/transport/smtp/commands.rs b/src/transport/smtp/commands.rs
index 56e31f9..f5d06b2 100644
--- a/src/transport/smtp/commands.rs
+++ b/src/transport/smtp/commands.rs
@@ -1,5 +1,7 @@
 //! SMTP commands
 
+use std::fmt::{self, Display, Formatter};
+
 use crate::{
     address::Address,
     transport::smtp::{
@@ -9,7 +11,6 @@ use crate::{
         response::Response,
     },
 };
-use std::fmt::{self, Display, Formatter};
 
 /// EHLO command
 #[derive(PartialEq, Clone, Debug)]
@@ -288,9 +289,10 @@ impl Auth {
 
 #[cfg(test)]
 mod test {
+    use std::str::FromStr;
+
     use super::*;
     use crate::transport::smtp::extension::MailBodyParameter;
-    use std::str::FromStr;
 
     #[test]
     fn test_display() {
diff --git a/src/transport/smtp/error.rs b/src/transport/smtp/error.rs
index 555cb42..375c03a 100644
--- a/src/transport/smtp/error.rs
+++ b/src/transport/smtp/error.rs
@@ -1,10 +1,11 @@
 //! Error and result type for SMTP clients
 
+use std::{error::Error as StdError, fmt};
+
 use crate::{
     transport::smtp::response::{Code, Severity},
     BoxError,
 };
-use std::{error::Error as StdError, fmt};
 
 // Inspired by https://github.com/seanmonstar/reqwest/blob/a8566383168c0ef06c21f38cbc9213af6ff6db31/src/error.rs
 
diff --git a/src/transport/smtp/extension.rs b/src/transport/smtp/extension.rs
index 2c88126..8af14cf 100644
--- a/src/transport/smtp/extension.rs
+++ b/src/transport/smtp/extension.rs
@@ -1,17 +1,18 @@
 //! ESMTP features
 
+use std::{
+    collections::HashSet,
+    fmt::{self, Display, Formatter},
+    net::{Ipv4Addr, Ipv6Addr},
+    result::Result,
+};
+
 use crate::transport::smtp::{
     authentication::Mechanism,
     error::{self, Error},
     response::Response,
     util::XText,
 };
-use std::{
-    collections::HashSet,
-    fmt::{self, Display, Formatter},
-    net::{Ipv4Addr, Ipv6Addr},
-    result::Result,
-};
 
 /// Client identifier, the parameter to `EHLO`
 #[derive(PartialEq, Eq, Clone, Debug)]
@@ -292,12 +293,13 @@ impl Display for RcptParameter {
 #[cfg(test)]
 mod test {
 
+    use std::collections::HashSet;
+
     use super::*;
     use crate::transport::smtp::{
         authentication::Mechanism,
         response::{Category, Code, Detail, Response, Severity},
     };
-    use std::collections::HashSet;
 
     #[test]
     fn test_clientid_fmt() {
diff --git a/src/transport/smtp/mod.rs b/src/transport/smtp/mod.rs
index c2cac3e..16b7f5f 100644
--- a/src/transport/smtp/mod.rs
+++ b/src/transport/smtp/mod.rs
@@ -33,7 +33,7 @@
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
-//! use lettre::{Message, Transport, SmtpTransport};
+//! use lettre::{Message, SmtpTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
@@ -43,8 +43,7 @@
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Create TLS transport on port 465
-//! let sender = SmtpTransport::relay("smtp.example.com")?
-//!     .build();
+//! let sender = SmtpTransport::relay("smtp.example.com")?.build();
 //! // Send the email via remote relay
 //! let result = sender.send(&email);
 //! assert!(result.is_ok());
@@ -59,7 +58,13 @@
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
-//! use lettre::{Message, Transport, SmtpTransport, transport::smtp::{PoolConfig, authentication::{Credentials, Mechanism}}};
+//! use lettre::{
+//!     transport::smtp::{
+//!         authentication::{Credentials, Mechanism},
+//!         PoolConfig,
+//!     },
+//!     Message, SmtpTransport, Transport,
+//! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
@@ -71,11 +76,14 @@
 //! // Create TLS transport on port 587 with STARTTLS
 //! let sender = SmtpTransport::starttls_relay("smtp.example.com")?
 //!     // Add credentials for authentication
-//!     .credentials(Credentials::new("username".to_string(), "password".to_string()))
+//!     .credentials(Credentials::new(
+//!         "username".to_string(),
+//!         "password".to_string(),
+//!     ))
 //!     // Configure expected authentication mechanism
 //!     .authentication(vec![Mechanism::Plain])
 //!     // Connection pool settings
-//!     .pool_config( PoolConfig::new().max_size(20))
+//!     .pool_config(PoolConfig::new().max_size(20))
 //!     .build();
 //!
 //! // Send the email via remote relay
@@ -90,7 +98,10 @@
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
-//! use lettre::{Message, Transport, SmtpTransport, transport::smtp::client::{TlsParameters, Tls}};
+//! use lettre::{
+//!     transport::smtp::client::{Tls, TlsParameters},
+//!     Message, SmtpTransport, Transport,
+//! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
@@ -101,7 +112,8 @@
 //!
 //! // Custom TLS configuration
 //! let tls = TlsParameters::builder("smtp.example.com".to_string())
-//!           .dangerous_accept_invalid_certs(true).build()?;
+//!     .dangerous_accept_invalid_certs(true)
+//!     .build()?;
 //!
 //! // Create TLS transport on port 465
 //! let sender = SmtpTransport::relay("smtp.example.com")?
@@ -116,6 +128,10 @@
 //! # }
 //! ```
 
+use std::time::Duration;
+
+use client::Tls;
+
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 pub use self::async_transport::{AsyncSmtpTransport, AsyncSmtpTransportBuilder};
 #[cfg(feature = "pool")]
@@ -132,8 +148,6 @@ use crate::transport::smtp::{
     extension::ClientId,
     response::Response,
 };
-use client::Tls;
-use std::time::Duration;
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 mod async_transport;
diff --git a/src/transport/smtp/pool/async_impl.rs b/src/transport/smtp/pool/async_impl.rs
index b947a25..f771762 100644
--- a/src/transport/smtp/pool/async_impl.rs
+++ b/src/transport/smtp/pool/async_impl.rs
@@ -1,20 +1,22 @@
-use std::fmt::{self, Debug};
-use std::mem;
-use std::ops::{Deref, DerefMut};
-use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::{
+    fmt::{self, Debug},
+    mem,
+    ops::{Deref, DerefMut},
+    sync::Arc,
+    time::{Duration, Instant},
+};
 
-use futures_util::lock::Mutex;
-use futures_util::stream::{self, StreamExt};
+use futures_util::{
+    lock::Mutex,
+    stream::{self, StreamExt},
+};
 use once_cell::sync::OnceCell;
 
-use crate::executor::SpawnHandle;
-use crate::transport::smtp::async_transport::AsyncSmtpClient;
-use crate::Executor;
-
-use super::super::client::AsyncSmtpConnection;
-use super::super::Error;
-use super::PoolConfig;
+use super::{
+    super::{client::AsyncSmtpConnection, Error},
+    PoolConfig,
+};
+use crate::{executor::SpawnHandle, transport::smtp::async_transport::AsyncSmtpClient, Executor};
 
 pub struct Pool<E: Executor> {
     config: PoolConfig,
diff --git a/src/transport/smtp/pool/sync_impl.rs b/src/transport/smtp/pool/sync_impl.rs
index 40e0253..aea8350 100644
--- a/src/transport/smtp/pool/sync_impl.rs
+++ b/src/transport/smtp/pool/sync_impl.rs
@@ -1,15 +1,18 @@
-use std::fmt::{self, Debug};
-use std::ops::{Deref, DerefMut};
-use std::sync::{Arc, Mutex, TryLockError};
-use std::time::{Duration, Instant};
-use std::{mem, thread};
+use std::{
+    fmt::{self, Debug},
+    mem,
+    ops::{Deref, DerefMut},
+    sync::{Arc, Mutex, TryLockError},
+    thread,
+    time::{Duration, Instant},
+};
 
+use super::{
+    super::{client::SmtpConnection, Error},
+    PoolConfig,
+};
 use crate::transport::smtp::transport::SmtpClient;
 
-use super::super::client::SmtpConnection;
-use super::super::Error;
-use super::PoolConfig;
-
 pub struct Pool {
     config: PoolConfig,
     connections: Mutex<Vec<ParkedConnection>>,
diff --git a/src/transport/smtp/response.rs b/src/transport/smtp/response.rs
index a780aae..73ce167 100644
--- a/src/transport/smtp/response.rs
+++ b/src/transport/smtp/response.rs
@@ -1,7 +1,13 @@
 //! SMTP response, containing a mandatory return code and an optional text
 //! message
 
-use crate::transport::smtp::{error, Error};
+use std::{
+    fmt::{Display, Formatter, Result},
+    result,
+    str::FromStr,
+    string::ToString,
+};
+
 use nom::{
     branch::alt,
     bytes::streaming::{tag, take_until},
@@ -10,12 +16,8 @@ use nom::{
     sequence::{preceded, tuple},
     IResult,
 };
-use std::{
-    fmt::{Display, Formatter, Result},
-    result,
-    str::FromStr,
-    string::ToString,
-};
+
+use crate::transport::smtp::{error, Error};
 
 /// First digit indicates severity
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
diff --git a/src/transport/stub/mod.rs b/src/transport/stub/mod.rs
index 533f007..7b0a13f 100644
--- a/src/transport/stub/mod.rs
+++ b/src/transport/stub/mod.rs
@@ -28,12 +28,14 @@
 //! # }
 //! ```
 
+use std::{error::Error as StdError, fmt};
+
+#[cfg(any(feature = "tokio1", feature = "async-std1"))]
+use async_trait::async_trait;
+
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 use crate::AsyncTransport;
 use crate::{address::Envelope, Transport};
-#[cfg(any(feature = "tokio1", feature = "async-std1"))]
-use async_trait::async_trait;
-use std::{error::Error as StdError, fmt};
 
 #[derive(Debug, Copy, Clone)]
 pub struct Error;
diff --git a/tests/transport_file.rs b/tests/transport_file.rs
index db74301..76267fa 100644
--- a/tests/transport_file.rs
+++ b/tests/transport_file.rs
@@ -9,13 +9,15 @@ fn default_date() -> std::time::SystemTime {
 #[cfg(test)]
 #[cfg(all(feature = "file-transport", feature = "builder"))]
 mod sync {
-    use crate::default_date;
-    use lettre::{FileTransport, Message, Transport};
     use std::{
         env::temp_dir,
         fs::{read_to_string, remove_file},
     };
 
+    use lettre::{FileTransport, Message, Transport};
+
+    use crate::default_date;
+
     #[test]
     fn file_transport() {
         let sender = FileTransport::new(temp_dir());
@@ -104,15 +106,16 @@ mod sync {
 #[cfg(test)]
 #[cfg(all(feature = "file-transport", feature = "builder", feature = "tokio1"))]
 mod tokio_1 {
-    use crate::default_date;
-    use lettre::{AsyncFileTransport, AsyncTransport, Message, Tokio1Executor};
     use std::{
         env::temp_dir,
         fs::{read_to_string, remove_file},
     };
 
+    use lettre::{AsyncFileTransport, AsyncTransport, Message, Tokio1Executor};
     use tokio1_crate as tokio;
 
+    use crate::default_date;
+
     #[tokio::test]
     async fn file_transport_tokio1() {
         let sender = AsyncFileTransport::<Tokio1Executor>::new(temp_dir());
@@ -155,13 +158,15 @@ mod tokio_1 {
     feature = "async-std1"
 ))]
 mod asyncstd_1 {
-    use crate::default_date;
-    use lettre::{AsyncFileTransport, AsyncStd1Executor, AsyncTransport, Message};
     use std::{
         env::temp_dir,
         fs::{read_to_string, remove_file},
     };
 
+    use lettre::{AsyncFileTransport, AsyncStd1Executor, AsyncTransport, Message};
+
+    use crate::default_date;
+
     #[async_std::test]
     async fn file_transport_asyncstd1() {
         let sender = AsyncFileTransport::<AsyncStd1Executor>::new(temp_dir());
diff --git a/tests/transport_smtp.rs b/tests/transport_smtp.rs
index d639f11..548d142 100644
--- a/tests/transport_smtp.rs
+++ b/tests/transport_smtp.rs
@@ -24,7 +24,6 @@ mod sync {
 #[cfg(all(feature = "smtp-transport", feature = "builder", feature = "tokio1"))]
 mod tokio_1 {
     use lettre::{AsyncSmtpTransport, AsyncTransport, Message, Tokio1Executor};
-
     use tokio1_crate as tokio;
 
     #[tokio::test]
diff --git a/tests/transport_smtp_pool.rs b/tests/transport_smtp_pool.rs
index d0ea3e9..d6eb07b 100644
--- a/tests/transport_smtp_pool.rs
+++ b/tests/transport_smtp_pool.rs
@@ -1,8 +1,9 @@
 #[cfg(all(test, feature = "smtp-transport", feature = "pool"))]
 mod sync {
-    use lettre::{address::Envelope, SmtpTransport, Transport};
     use std::{sync::mpsc, thread};
 
+    use lettre::{address::Envelope, SmtpTransport, Transport};
+
     fn envelope() -> Envelope {
         Envelope::new(
             Some("user@localhost".parse().unwrap()),
diff --git a/tests/transport_stub.rs b/tests/transport_stub.rs
index 32a624a..01b7119 100644
--- a/tests/transport_stub.rs
+++ b/tests/transport_stub.rs
@@ -24,7 +24,6 @@ mod sync {
 #[cfg(all(feature = "builder", feature = "tokio1"))]
 mod tokio_1 {
     use lettre::{transport::stub::StubTransport, AsyncTransport, Message};
-
     use tokio1_crate as tokio;
 
     #[tokio::test]