// New returns a new *Mailer, which contains the Send methods.
New(cfg Config) *Mailer

// SendWithBytes same as `Send` but it accepts the body as raw []byte,
// it's the fastest method to send e-mails.
SendWithBytes(subject string, body []byte, to ...string) error 

// Send sends an email to the recipient(s)
// the body can be in HTML format as well.
Send(subject string, body string, to ...string) error

// SendWithReader same as `Send` but it accepts
// an io.Reader that body can be retrieved and call the `SendWithBytes`.
SendWithReader(subject string, bodyReader io.Reader, to ...string) error

// SendWithReadCloser same as `SendWithReader` but it closes the reader at the end.
SendWithReadCloser(subject string, bodyReader io.ReadCloser, to ...string) error

// Config contains those necessary fields that Mailer needs to send e-mails.
type Config struct {
    // Host is the server mail host, IP or address.
    Host string
    // Port is the listening port.
    Port int
    // Username is the auth [email protected] for the sender.
    Username string
    // Password is the auth password for the sender.
    Password string
    // FromAddr is the 'from' part of the mail header, it overrides the username.
    FromAddr string
    // FromAlias is the from part, if empty this is the first part before @ from the Username field.
    FromAlias string
    // UseCommand enable it if you want to send e-mail with the mail command  instead of smtp.
    //
    // Host,Port & Password will be ignored.
    // ONLY FOR UNIX.
    UseCommand bool
}

package main

import "github.com/kataras/go-mailer"

func main() {
    // sender configuration.
    config := mailer.Config{
        Host:     "smtp.mailgun.org",
        Username: "postmaster",
        Password: "38304272b8ee5c176d5961dc155b2417",
        FromAddr: "[email protected]",
        Port:     587,
        // Enable UseCommand to support sendmail unix command,
        // if this field is true then Host, Username, Password and Port are not required,
        // because these info already exists in your local sendmail configuration.
        //
        // Defaults to false.
        UseCommand: false,
    }

    // initalize a new mail sender service.
    sender := mailer.New(config)

    // the subject/title of the e-mail.
    subject := "Hello subject"

    // the rich message body.
    content := `<h1>Hello</h1> <br/><br/> <span style="color:red"> This is the rich message body </span>`

    // the recipient(s).
    to := []string{"[email protected]", "[email protected]"}

    // send the e-mail.
    err := sender.Send(subject, content, to...)

    if err != nil {
        println("error while sending the e-mail: " + err.Error())
    }
}

sender := mailer.New(mailer.Config{...})
to := []string{"[email protected]", "[email protected]"}
sender.Send("subject", "<p>body</p>", to...)