diff --git a/lettre/src/sendmail/mod.rs b/lettre/src/sendmail/mod.rs
index c594a73..14c107e 100644
--- a/lettre/src/sendmail/mod.rs
+++ b/lettre/src/sendmail/mod.rs
@@ -5,6 +5,7 @@ use crate::sendmail::error::SendmailResult;
 use crate::SendableEmail;
 use crate::Transport;
 use log::info;
+use std::convert::AsRef;
 use std::io::prelude::*;
 use std::io::Read;
 use std::process::{Command, Stdio};
@@ -47,13 +48,7 @@ impl<'a> Transport<'a> for SendmailTransport {
         let mut process = Command::new(&self.command)
             .arg("-i")
             .arg("-f")
-            .arg(
-                email
-                    .envelope()
-                    .from()
-                    .map(|x| x.as_ref())
-                    .unwrap_or("\"\""),
-            )
+            .arg(email.envelope().from().map(AsRef::as_ref).unwrap_or("\"\""))
             .args(email.envelope.to())
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
diff --git a/lettre/src/smtp/commands.rs b/lettre/src/smtp/commands.rs
index 8cda6af..0e04921 100644
--- a/lettre/src/smtp/commands.rs
+++ b/lettre/src/smtp/commands.rs
@@ -1,4 +1,3 @@
-
 //! SMTP commands
 
 use crate::smtp::authentication::{Credentials, Mechanism};
@@ -9,6 +8,7 @@ use crate::smtp::response::Response;
 use crate::EmailAddress;
 use base64;
 use log::debug;
+use std::convert::AsRef;
 use std::fmt::{self, Display, Formatter};
 
 /// EHLO command
@@ -64,7 +64,7 @@ impl Display for MailCommand {
         write!(
             f,
             "MAIL FROM:<{}>",
-            self.sender.as_ref().map(|x| x.as_ref()).unwrap_or("")
+            self.sender.as_ref().map(AsRef::as_ref).unwrap_or("")
         )?;
         for parameter in &self.parameters {
             write!(f, " {}", parameter)?;
diff --git a/lettre/src/smtp/response.rs b/lettre/src/smtp/response.rs
index 9527067..69aff35 100644
--- a/lettre/src/smtp/response.rs
+++ b/lettre/src/smtp/response.rs
@@ -6,6 +6,7 @@ use nom::{crlf, ErrorKind as NomErrorKind};
 use std::fmt::{Display, Formatter, Result};
 use std::result;
 use std::str::{from_utf8, FromStr};
+use std::string::ToString;
 
 /// First digit indicates severity
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
@@ -269,7 +270,7 @@ named!(
                 code: last_code,
                 message: lines
                     .into_iter()
-                    .map(|line| from_utf8(line).map(|s| s.to_string()))
+                    .map(|line| from_utf8(line).map(ToString::to_string))
                     .collect::<result::Result<Vec<_>, _>>()
                     .map_err(|_| ())?,
             })
diff --git a/lettre_email/src/lib.rs b/lettre_email/src/lib.rs
index 9d928da..05d25a9 100644
--- a/lettre_email/src/lib.rs
+++ b/lettre_email/src/lib.rs
@@ -19,6 +19,7 @@ use crate::error::Error;
 pub use email::{Address, Header, Mailbox, MimeMessage, MimeMultipartType};
 use lettre::{error::Error as LettreError, EmailAddress, Envelope, SendableEmail};
 use mime::Mime;
+use std::ffi::OsStr;
 use std::fs;
 use std::path::Path;
 use std::str::FromStr;
@@ -250,7 +251,7 @@ impl EmailBuilder {
             fs::read(path)?.as_slice(),
             filename.unwrap_or(
                 path.file_name()
-                    .and_then(|x| x.to_str())
+                    .and_then(OsStr::to_str)
                     .ok_or(Error::CannotParseFilename)?,
             ),
             content_type,
diff --git a/lettre_email/tests/skeptic.rs b/lettre_email/tests/skeptic.rs
index 33756b4..43ed564 100644
--- a/lettre_email/tests/skeptic.rs
+++ b/lettre_email/tests/skeptic.rs
@@ -8,13 +8,13 @@ use std::process::Command;
 fn book_test() {
     let mut book_path = env::current_dir().unwrap();
     let readme = Path::new(file!())
-            .parent()
-            .unwrap()
-            .parent()
-            .unwrap()
-            .parent()
-            .unwrap()
-            .join("../README.md");
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .join("../README.md");
     book_path.push(
         Path::new(file!())
             .parent()