docs: add missing ContentType to email building (#1017)

benches/transport_smtp.rs

@@ -1,5 +1,5 @@
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use lettre::{Message, SmtpTransport, Transport};
+use lettre::{message::header::ContentType, Message, SmtpTransport, Transport};
 
 fn bench_simple_send(c: &mut Criterion) {
     let sender = SmtpTransport::builder_dangerous("127.0.0.1")
@@ -13,6 +13,7 @@ fn bench_simple_send(c: &mut Criterion) {
                 .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
                 .to("Hei <hei@domain.tld>".parse().unwrap())
                 .subject("Happy new year")
+                .header(ContentType::TEXT_PLAIN)
                 .body(String::from("Be happy!"))
                 .unwrap();
             let result = black_box(sender.send(&email));
@@ -32,6 +33,7 @@ fn bench_reuse_send(c: &mut Criterion) {
                 .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
                 .to("Hei <hei@domain.tld>".parse().unwrap())
                 .subject("Happy new year")
+                .header(ContentType::TEXT_PLAIN)
                 .body(String::from("Be happy!"))
                 .unwrap();
             let result = black_box(sender.send(&email));

src/message/mod.rs

@@ -537,7 +537,10 @@ impl Message {
     /// Example:
     /// ```rust
     /// use lettre::{
-    ///     message::dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey},
+    ///     message::{
+    ///         dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey},
+    ///         header::ContentType,
+    ///     },
     ///     Message,
     /// };
     ///
@@ -546,6 +549,7 @@ impl Message {
     ///     .reply_to("Bob <bob@example.org>".parse().unwrap())
     ///     .to("Carla <carla@example.net>".parse().unwrap())
     ///     .subject("Hello")
+    ///     .header(ContentType::TEXT_PLAIN)
     ///     .body("Hi there, it's a test email, with utf-8 chars ë!\n\n\n".to_owned())
     ///     .unwrap();
     /// let key = "-----BEGIN RSA PRIVATE KEY-----

src/transport/file/mod.rs

@@ -11,7 +11,7 @@
 //! # fn main() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{FileTransport, Message, Transport};
+//! use lettre::{message::header::ContentType, FileTransport, Message, Transport};
 //!
 //! // Write to the local temp directory
 //! let sender = FileTransport::new(temp_dir());
@@ -20,6 +20,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let result = sender.send(&email);
@@ -44,7 +45,7 @@
 //! # fn main() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{FileTransport, Message, Transport};
+//! use lettre::{message::header::ContentType, FileTransport, Message, Transport};
 //!
 //! // Write to the local temp directory
 //! let sender = FileTransport::with_envelope(temp_dir());
@@ -53,6 +54,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let result = sender.send(&email);
@@ -73,7 +75,9 @@
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{AsyncFileTransport, AsyncTransport, Message, Tokio1Executor};
+//! use lettre::{
+//!     message::header::ContentType, AsyncFileTransport, AsyncTransport, Message, Tokio1Executor,
+//! };
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<Tokio1Executor>::new(temp_dir());
@@ -82,6 +86,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let result = sender.send(email).await;
@@ -99,7 +104,10 @@
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{AsyncFileTransport, AsyncStd1Executor, AsyncTransport, Message};
+//! use lettre::{
+//!     message::header::ContentType, AsyncFileTransport, AsyncStd1Executor, AsyncTransport,
+//!     Message,
+//! };
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<AsyncStd1Executor>::new(temp_dir());
@@ -108,6 +116,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let result = sender.send(email).await;
@@ -125,6 +134,7 @@
 //! Reply-To: Yuin <yuin@domain.tld>
 //! To: Hei <hei@domain.tld>
 //! Subject: Happy new year
+//! Content-Type: text/plain; charset=utf-8
 //! Date: Tue, 18 Aug 2020 22:50:17 GMT
 //!
 //! Be happy!

src/transport/mod.rs

@@ -56,13 +56,17 @@
 //! #
 //! # #[cfg(all(feature = "builder", feature = "smtp-transport"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{transport::smtp::authentication::Credentials, Message, SmtpTransport, Transport};
+//! use lettre::{
+//!     message::header::ContentType, transport::smtp::authentication::Credentials, Message,
+//!     SmtpTransport, Transport,
+//! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let creds = Credentials::new("smtp_username".to_owned(), "smtp_password".to_owned());

src/transport/sendmail/mod.rs

@@ -7,13 +7,14 @@
 //! #
 //! # #[cfg(all(feature = "sendmail-transport", feature = "builder"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{Message, SendmailTransport, Transport};
+//! use lettre::{message::header::ContentType, Message, SendmailTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = SendmailTransport::new();
@@ -34,7 +35,8 @@
 //! # #[cfg(all(feature = "tokio1", feature = "sendmail-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use lettre::{
-//!     AsyncSendmailTransport, AsyncTransport, Message, SendmailTransport, Tokio1Executor,
+//!     message::header::ContentType, AsyncSendmailTransport, AsyncTransport, Message,
+//!     SendmailTransport, Tokio1Executor,
 //! };
 //!
 //! let email = Message::builder()
@@ -42,6 +44,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = AsyncSendmailTransport::<Tokio1Executor>::new();
@@ -58,13 +61,13 @@
 //! #
 //! # #[cfg(all(feature = "async-std1", feature = "sendmail-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
-//! use lettre::{Message, AsyncTransport, AsyncStd1Executor, AsyncSendmailTransport};
+//! use lettre::{Message, AsyncTransport, AsyncStd1Executor,message::header::ContentType, AsyncSendmailTransport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
-//!     .subject("Happy new year")
+//!     .subject("Happy new year").header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = AsyncSendmailTransport::<AsyncStd1Executor>::new();

src/transport/smtp/mod.rs

@@ -33,13 +33,14 @@
 //! ```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, SmtpTransport, Transport};
+//! use lettre::{message::header::ContentType, Message, SmtpTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Create TLS transport on port 465
@@ -59,6 +60,7 @@
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use lettre::{
+//!     message::header::ContentType,
 //!     transport::smtp::{
 //!         authentication::{Credentials, Mechanism},
 //!         PoolConfig,
@@ -71,6 +73,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Create TLS transport on port 587 with STARTTLS
@@ -99,6 +102,7 @@
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use lettre::{
+//!     message::header::ContentType,
 //!     transport::smtp::client::{Tls, TlsParameters},
 //!     Message, SmtpTransport, Transport,
 //! };
@@ -108,6 +112,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Custom TLS configuration

src/transport/stub/mod.rs

@@ -11,7 +11,9 @@
 //! ```rust
 //! # #[cfg(feature = "builder")]
 //! # {
-//! use lettre::{transport::stub::StubTransport, Message, Transport};
+//! use lettre::{
+//!     message::header::ContentType, transport::stub::StubTransport, Message, Transport,
+//! };
 //!
 //! # use std::error::Error;
 //! # fn try_main() -> Result<(), Box<dyn Error>> {
@@ -20,6 +22,7 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
+//!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let mut sender = StubTransport::new_ok();