Fix clippy and formatting

lettre_email/examples/smtp_gmail.rs

@@ -1,38 +0,0 @@
-extern crate lettre;
-extern crate lettre_email;
-
-use lettre::smtp::authentication::Credentials;
-use lettre::{SmtpClient, Transport};
-use lettre_email::Email;
-
-fn main() {
-    let email = Email::builder()
-        .to("to@example.org")
-        .from("from@example.com")
-        .subject("subject")
-        .text("message")
-        .build()
-        .unwrap();
-
-    let creds = Credentials::new(
-        "example_username".to_string(),
-        "example_password".to_string(),
-    );
-
-    // Open connection to gmail
-    let mut mailer = SmtpClient::new_simple("smtp.gmail.com")
-        .unwrap()
-        .credentials(creds)
-        .transport();
-
-    // Send the email
-    let result = mailer.send(email.into());
-
-    if result.is_ok() {
-        println!("Email sent");
-    } else {
-        println!("Could not send email: {:?}", result);
-    }
-
-    assert!(result.is_ok());
-}