mail

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 Go to latest Published: Oct 31, 2024 License: MIT Imports: 19 Imported by: 0

README

Gomail

Build Status Code Coverage Documentation

This is an actively maintained fork of Gomail and includes fixes and improvements for a number of outstanding issues. The current progress is as follows:

  • Timeouts and retries can be specified outside of the 10 second default.
  • Proxying is supported through specifying a custom NetDialTimeout.
  • Filenames are properly encoded for non-ASCII characters.
  • Email addresses are properly encoded for non-ASCII characters.
  • Embedded files and attachments are tested for their existence.
  • An io.Reader can be supplied when embedding and attaching files.

See Transitioning Existing Codebases for more information on switching.

Introduction

Gomail is a simple and efficient package to send emails. It is well tested and documented.

Gomail can only send emails using an SMTP server. But the API is flexible and it is easy to implement other methods for sending emails using a local Postfix, an API, etc.

It requires Go 1.2 or newer. With Go 1.5, no external dependencies are used.

Features

Gomail supports:

  • Attachments
  • Embedded images
  • HTML and text templates
  • Automatic encoding of special characters
  • SSL and TLS
  • Sending multiple emails with the same SMTP connection

Documentation

https://godoc.org/github.com/go-mail/mail

Download

If you're already using a dependency manager, like dep, use the following import path:

github.com/go-mail/mail

If you aren't using vendoring, go get the Gopkg.in import path:

gopkg.in/mail.v2

Examples

See the examples in the documentation.

FAQ

x509: certificate signed by unknown authority

If you get this error it means the certificate used by the SMTP server is not considered valid by the client running Gomail. As a quick workaround you can bypass the verification of the server's certificate chain and host name by using SetTLSConfig:

package main

import (
	"crypto/tls"

	"gopkg.in/mail.v2"
)

func main() {
	d := mail.NewDialer("smtp.example.com", 587, "user", "123456")
	d.TLSConfig = &tls.Config{InsecureSkipVerify: true}

	// Send emails using d.
}

Note, however, that this is insecure and should not be used in production.

Transitioning Existing Codebases

If you're already using the original Gomail, switching is as easy as updating the import line to:

import gomail "gopkg.in/mail.v2"

Contribute

Contributions are more than welcome! See CONTRIBUTING.md for more info.

Change log

See CHANGELOG.md.

License

MIT

Support & Contact

You can ask questions on the Gomail thread in the Go mailing-list.

Documentation

Overview

Package gomail provides a simple interface to compose emails and to mail them efficiently.

More info on Github: https://github.com/go-mail/mail

Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321. It also implements the following extensions: 

8BITMIME  RFC 1652
AUTH      RFC 2554
STARTTLS  RFC 3207

Additional extensions may be handled by clients.

The smtp package is frozen and is not accepting new features. Some external packages provide more functionality. See: 

https://godoc.org/?q=smtp
Example 
m := mail.NewMessage()
m.SetHeader("From", "alex@example.com")
m.SetHeader("To", "bob@example.com", "cora@example.com")
m.SetAddressHeader("Cc", "dan@example.com", "Dan")
m.SetHeader("Subject", "Hello!")
m.SetBody("text/html", "Hello <b>Bob</b> and <i>Cora</i>!")
m.Attach("/home/Alex/lolcat.jpg")

d := mail.NewDialer("smtp.example.com", 587, "user", "123456")
d.StartTLSPolicy = mail.MandatoryStartTLS

// Send the email to Bob, Cora and Dan.
if err := d.DialAndSend(m); err != nil {
	panic(err)
}

Output:
Example (Daemon)

A daemon that listens to a channel and sends all incoming messages. 

ch := make(chan *mail.Message)

go func() {
	d := mail.NewDialer("smtp.example.com", 587, "user", "123456")
	d.StartTLSPolicy = mail.MandatoryStartTLS

	var s mail.SendCloser
	var err error
	open := false
	for {
		select {
		case m, ok := <-ch:
			if !ok {
				return
			}
			if !open {
				if s, err = d.Dial(); err != nil {
					panic(err)
				}
				open = true
			}
			if err := mail.Send(s, m); err != nil {
				log.Print(err)
			}
		// Close the connection to the SMTP server if no email was sent in
		// the last 30 seconds.
		case <-time.After(30 * time.Second):
			if open {
				if err := s.Close(); err != nil {
					panic(err)
				}
				open = false
			}
		}
	}
}()

// Use the channel in your program to send emails.

// Close the channel to stop the mail daemon.
close(ch)

Output:
Example (Newsletter)

Efficiently send a customized newsletter to a list of recipients. 

// The list of recipients.
var list []struct {
	Name    string
	Address string
}

d := mail.NewDialer("smtp.example.com", 587, "user", "123456")
d.StartTLSPolicy = mail.MandatoryStartTLS
s, err := d.Dial()
if err != nil {
	panic(err)
}

m := mail.NewMessage()
for _, r := range list {
	m.SetHeader("From", "no-reply@example.com")
	m.SetAddressHeader("To", r.Address, r.Name)
	m.SetHeader("Subject", "Newsletter #1")
	m.SetBody("text/html", fmt.Sprintf("Hello %s!", r.Name))

	if err := mail.Send(s, m); err != nil {
		log.Printf("Could not send email to %q: %v", r.Address, err)
	}
	m.Reset()
}

Output:
Example (NoAuth)

Send an email using a local SMTP server. 

m := mail.NewMessage()
m.SetHeader("From", "from@example.com")
m.SetHeader("To", "to@example.com")
m.SetHeader("Subject", "Hello!")
m.SetBody("text/plain", "Hello!")

d := mail.Dialer{Host: "localhost", Port: 587}
if err := d.DialAndSend(m); err != nil {
	panic(err)
}

Output:
Example (NoSMTP)

Send an email using an API or postfix. 

m := mail.NewMessage()
m.SetHeader("From", "from@example.com")
m.SetHeader("To", "to@example.com")
m.SetHeader("Subject", "Hello!")
m.SetBody("text/plain", "Hello!")

s := mail.SendFunc(func(from string, to []string, msg io.WriterTo) error {
	// Implements you email-sending function, for example by calling
	// an API, or running postfix, etc.
	fmt.Println("From:", from)
	fmt.Println("To:", to)
	return nil
})

if err := mail.Send(s, m); err != nil {
	panic(err)
}

Output:

From: from@example.com
To: [to@example.com]

Index

Examples

Constants

This section is empty.

Variables

View Source 
var NetDialTimeout = net.DialTimeout

NetDialTimeout specifies the DialTimeout function to establish a connection to the SMTP server. This can be used to override dialing in the case that a proxy or other special behavior is needed.

Functions

func Send 

func Send(s Sender, msg ...*Message) error

Send sends emails using the given Sender.

func SendMail 

func SendMail(addr string, a Auth, from string, to []string, msg []byte) error

SendMail connects to the server at addr, switches to TLS if possible, authenticates with the optional mechanism a if possible, and then sends an email from address from, to addresses to, with message msg. The addr must include a port, as in "mail.example.com:smtp".

The addresses in the to parameter are the SMTP RCPT addresses.

The msg parameter should be an RFC 822-style email with headers first, a blank line, and then the message body. The lines of msg should be CRLF terminated. The msg headers should usually include fields such as "From", "To", "Subject", and "Cc". Sending "Bcc" messages is accomplished by including an email address in the to parameter but not including it in the msg headers.

The SendMail function and the net/smtp package are low-level mechanisms and provide no support for DKIM signing, MIME attachments (see the mime/multipart package), or other mail functionality. Higher-level packages exist outside of the standard library.

Types

type Auth 

type Auth interface {
	// Start begins an authentication with a server.
	// It returns the name of the authentication protocol
	// and optionally data to include in the initial AUTH message
	// sent to the server.
	// If it returns a non-nil error, the SMTP client aborts
	// the authentication attempt and closes the connection.
	Start(server *ServerInfo) (proto string, toServer []byte, err error)

	// Next continues the authentication. The server has just sent
	// the fromServer data. If more is true, the server expects a
	// response, which Next should return as toServer; otherwise
	// Next should return toServer == nil.
	// If Next returns a non-nil error, the SMTP client aborts
	// the authentication attempt and closes the connection.
	Next(fromServer []byte, more bool) (toServer []byte, err error)
}

Auth is implemented by an SMTP authentication mechanism.

func CRAMMD5Auth 

func CRAMMD5Auth(username, secret string) Auth

CRAMMD5Auth returns an Auth that implements the CRAM-MD5 authentication mechanism as defined in RFC 2195. The returned Auth uses the given username and secret to authenticate to the server using the challenge-response mechanism.

func PlainAuth 

func PlainAuth(identity, username, password, host string) Auth

PlainAuth returns an Auth that implements the PLAIN authentication mechanism as defined in RFC 4616. The returned Auth uses the given username and password to authenticate to host and act as identity. Usually identity should be the empty string, to act as username.

PlainAuth will only send the credentials if the connection is using TLS or is connected to localhost. Otherwise authentication will fail with an error, without sending the credentials.

type Client 

type Client struct {
	// Text is the textproto.Conn used by the Client. It is exported to allow for
	// clients to add extensions.
	Text *textproto.Conn
	// contains filtered or unexported fields
}

A Client represents a client connection to an SMTP server.

func Dial 

func Dial(addr string) (*Client, error)

Dial returns a new Client connected to an SMTP server at addr. The addr must include a port, as in "mail.example.com:smtp".

func NewClient 

func NewClient(conn net.Conn, host string) (*Client, error)

NewClient returns a new Client using an existing connection and host as a server name to be used when authenticating.

func (*Client) Auth 

func (c *Client) Auth(a Auth) error

Auth authenticates a client using the provided authentication mechanism. A failed authentication closes the connection. Only servers that advertise the AUTH extension support this function.

func (*Client) Close 

func (c *Client) Close() error

Close closes the connection.

func (*Client) Data 

func (c *Client) Data() (io.WriteCloser, error)

Data issues a DATA command to the server and returns a writer that can be used to write the mail headers and body. The caller should close the writer before calling any more methods on c. A call to Data must be preceded by one or more calls to Client.Rcpt.

func (*Client) Extension 

func (c *Client) Extension(ext string) (bool, string)

Extension reports whether an extension is support by the server. The extension name is case-insensitive. If the extension is supported, Extension also returns a string that contains any parameters the server specifies for the extension.

func (*Client) Hello 

func (c *Client) Hello(localName string) error

Hello sends a HELO or EHLO to the server as the given host name. Calling this method is only necessary if the client needs control over the host name used. The client will introduce itself as "localhost" automatically otherwise. If Hello is called, it must be called before any of the other methods.

func (*Client) Mail 

func (c *Client) Mail(from string) error

Mail issues a MAIL command to the server using the provided email address. If the server supports the 8BITMIME extension, Mail adds the BODY=8BITMIME parameter. If the server supports the SMTPUTF8 extension, Mail adds the SMTPUTF8 parameter. This initiates a mail transaction and is followed by one or more Client.Rcpt calls.

func (*Client) Noop 

func (c *Client) Noop() error

Noop sends the NOOP command to the server. It does nothing but check that the connection to the server is okay.

func (*Client) Quit 

func (c *Client) Quit() error

Quit sends the QUIT command and closes the connection to the server.

func (*Client) Rcpt 

func (c *Client) Rcpt(to string) error

Rcpt issues a RCPT command to the server using the provided email address. A call to Rcpt must be preceded by a call to Client.Mail and may be followed by a Client.Data call or another Rcpt call.

func (*Client) Reset 

func (c *Client) Reset() error

Reset sends the RSET command to the server, aborting the current mail transaction.

func (*Client) StartTLS 

func (c *Client) StartTLS(config *tls.Config) error

StartTLS sends the STARTTLS command and encrypts all further communication. Only servers that advertise the STARTTLS extension support this function.

func (*Client) TLSConnectionState 

func (c *Client) TLSConnectionState() (state tls.ConnectionState, ok bool)

TLSConnectionState returns the client's TLS connection state. The return values are their zero values if Client.StartTLS did not succeed.

func (*Client) Verify 

func (c *Client) Verify(addr string) error

Verify checks the validity of an email address on the server. If Verify returns nil, the address is valid. A non-nil return does not necessarily indicate an invalid address. Many servers will not verify addresses for security reasons.

type Dialer 

type Dialer struct {
	// Host represents the host of the SMTP server.
	Host string
	// Port represents the port of the SMTP server.
	Port int
	// Username is the username to use to authenticate to the SMTP server.
	Username string
	// Password is the password to use to authenticate to the SMTP server.
	Password string
	// Auth represents the authentication mechanism used to authenticate to the
	// SMTP server.
	Auth Auth
	// SSL defines whether an SSL connection is used. It should be false in
	// most cases since the authentication mechanism should use the STARTTLS
	// extension instead.
	SSL bool
	// TLSConfig represents the TLS configuration used for the TLS (when the
	// STARTTLS extension is used) or SSL connection.
	TLSConfig *tls.Config
	// StartTLSPolicy represents the TLS security level required to
	// communicate with the SMTP server.
	//
	// This defaults to OpportunisticStartTLS for backwards compatibility,
	// but we recommend MandatoryStartTLS for all modern SMTP servers.
	//
	// This option has no effect if SSL is set to true.
	StartTLSPolicy StartTLSPolicy
	// LocalName is the hostname sent to the SMTP server with the HELO command.
	// By default, "localhost" is sent.
	LocalName string
	// Timeout to use for read/write operations. Defaults to 10 seconds, can
	// be set to 0 to disable timeouts.
	Timeout time.Duration
	// Whether we should retry mailing if the connection returned an error,
	// defaults to true.
	RetryFailure bool
}

A Dialer is a dialer to an SMTP server.

func NewDialer 

func NewDialer(host string, port int, username, password string) *Dialer

NewDialer returns a new SMTP Dialer. The given parameters are used to connect to the SMTP server.

func NewPlainDialer deprecated 

func NewPlainDialer(host string, port int, username, password string) *Dialer

NewPlainDialer returns a new SMTP Dialer. The given parameters are used to connect to the SMTP server.

Deprecated: Use NewDialer instead.

func (*Dialer) Dial 

func (d *Dialer) Dial() (SendCloser, error)

Dial dials and authenticates to an SMTP server. The returned SendCloser should be closed when done using it.

func (*Dialer) DialAndSend 

func (d *Dialer) DialAndSend(m ...*Message) error

DialAndSend opens a connection to the SMTP server, sends the given emails and closes the connection.

type Encoding 

type Encoding string

Encoding represents a MIME encoding scheme like quoted-printable or base64. 

const (
	// QuotedPrintable represents the quoted-printable encoding as defined in
	// RFC 2045.
	QuotedPrintable Encoding = "quoted-printable"
	// Base64 represents the base64 encoding as defined in RFC 2045.
	Base64 Encoding = "base64"
	// Unencoded can be used to avoid encoding the body of an email. The headers
	// will still be encoded using quoted-printable encoding.
	Unencoded Encoding = "8bit"
)

type FileSetting 

type FileSetting func(*file)

A FileSetting can be used as an argument in Message.Attach or Message.Embed.

func Rename 

func Rename(name string) FileSetting

Rename is a file setting to set the name of the attachment if the name is different than the filename on disk.

Example 
m.Attach("/tmp/0000146.jpg", mail.Rename("picture.jpg"))

Output:

func SetCopyFunc 

func SetCopyFunc(f func(io.Writer) error) FileSetting

SetCopyFunc is a file setting to replace the function that runs when the message is sent. It should copy the content of the file to the io.Writer.

The default copy function opens the file with the given filename, and copy its content to the io.Writer.

Example 
m.Attach("foo.txt", mail.SetCopyFunc(func(w io.Writer) error {
	_, err := w.Write([]byte("Content of foo.txt"))
	return err
}))

Output:

func SetHeader 

func SetHeader(h map[string][]string) FileSetting

SetHeader is a file setting to set the MIME header of the message part that contains the file content.

Mandatory headers are automatically added if they are not set when sending the email.

Example 
h := map[string][]string{"Content-ID": {"<foo@bar.mail>"}}
m.Attach("foo.jpg", mail.SetHeader(h))

Output:

type Message 

type Message struct {
	// contains filtered or unexported fields
}

Message represents an email.

func NewMessage 

func NewMessage(settings ...MessageSetting) *Message

NewMessage creates a new message. It uses UTF-8 and quoted-printable encoding by default.

func (*Message) AddAlternative 

func (m *Message) AddAlternative(contentType, body string, settings ...PartSetting)

AddAlternative adds an alternative part to the message.

It is commonly used to send HTML emails that default to the plain text version for backward compatibility. AddAlternative appends the new part to the end of the message. So the plain text part should be added before the HTML part. See http://en.wikipedia.org/wiki/MIME#Alternative

Example 
m.SetBody("text/plain", "Hello!")
m.AddAlternative("text/html", "<p>Hello!</p>")

Output:

func (*Message) AddAlternativeWriter 

func (m *Message) AddAlternativeWriter(contentType string, f func(io.Writer) error, settings ...PartSetting)

AddAlternativeWriter adds an alternative part to the message. It can be useful with the text/template or html/template packages.

Example 
t := template.Must(template.New("example").Parse("Hello {{.}}!"))
m.AddAlternativeWriter("text/plain", func(w io.Writer) error {
	return t.Execute(w, "Bob")
})

Output:

func (*Message) Attach 

func (m *Message) Attach(filename string, settings ...FileSetting)

Attach attaches the files to the email.

Example 
m.Attach("/tmp/image.jpg")

Output:

func (*Message) AttachReader 

func (m *Message) AttachReader(name string, r io.Reader, settings ...FileSetting)

AttachReader attaches a file using an io.Reader

func (*Message) Embed 

func (m *Message) Embed(filename string, settings ...FileSetting)

Embed embeds the images to the email.

Example 
m.Embed("/tmp/image.jpg")
m.SetBody("text/html", `<img src="cid:image.jpg" alt="My image" />`)

Output:

func (*Message) EmbedReader 

func (m *Message) EmbedReader(name string, r io.Reader, settings ...FileSetting)

EmbedReader embeds the images to the email.

func (*Message) FormatAddress 

func (m *Message) FormatAddress(address, name string) string

FormatAddress formats an address and a name as a valid RFC 5322 address.

Example 
m.SetHeader("To", m.FormatAddress("bob@example.com", "Bob"), m.FormatAddress("cora@example.com", "Cora"))

Output:

func (*Message) FormatDate 

func (m *Message) FormatDate(date time.Time) string

FormatDate formats a date as a valid RFC 5322 date.

Example 
m.SetHeaders(map[string][]string{
	"X-Date": {m.FormatDate(time.Now())},
})

Output:

func (*Message) GetHeader 

func (m *Message) GetHeader(field string) []string

GetHeader gets a header field.

func (*Message) Reset 

func (m *Message) Reset()

Reset resets the message so it can be reused. The message keeps its previous settings so it is in the same state that after a call to NewMessage.

func (*Message) SetAddressHeader 

func (m *Message) SetAddressHeader(field, address, name string)

SetAddressHeader sets an address to the given header field.

Example 
m.SetAddressHeader("To", "bob@example.com", "Bob")

Output:

func (*Message) SetBody 

func (m *Message) SetBody(contentType, body string, settings ...PartSetting)

SetBody sets the body of the message. It replaces any content previously set by SetBody, SetBodyWriter, AddAlternative or AddAlternativeWriter.

Example 
m.SetBody("text/plain", "Hello!")

Output:

func (*Message) SetBodyWriter 

func (m *Message) SetBodyWriter(contentType string, f func(io.Writer) error, settings ...PartSetting)

SetBodyWriter sets the body of the message. It can be useful with the text/template or html/template packages.

Example 
t := template.Must(template.New("example").Parse("Hello {{.}}!"))
m.SetBodyWriter("text/plain", func(w io.Writer) error {
	return t.Execute(w, "Bob")
})

Output:

func (*Message) SetBoundary 

func (m *Message) SetBoundary(boundary string)

SetBoundary sets a custom multipart boundary.

func (*Message) SetDateHeader 

func (m *Message) SetDateHeader(field string, date time.Time)

SetDateHeader sets a date to the given header field.

Example 
m.SetDateHeader("X-Date", time.Now())

Output:

func (*Message) SetHeader 

func (m *Message) SetHeader(field string, value ...string)

SetHeader sets a value to the given header field.

Example 
m.SetHeader("Subject", "Hello!")

Output:

func (*Message) SetHeaders 

func (m *Message) SetHeaders(h map[string][]string)

SetHeaders sets the message headers.

Example 
m.SetHeaders(map[string][]string{
	"From":    {m.FormatAddress("alex@example.com", "Alex")},
	"To":      {"bob@example.com", "cora@example.com"},
	"Subject": {"Hello"},
})

Output:

func (*Message) WriteTo 

func (m *Message) WriteTo(w io.Writer) (int64, error)

WriteTo implements io.WriterTo. It dumps the whole message into w.

type MessageSetting 

type MessageSetting func(m *Message)

A MessageSetting can be used as an argument in NewMessage to configure an email.

func SetCharset 

func SetCharset(charset string) MessageSetting

SetCharset is a message setting to set the charset of the email.

Example 
m = mail.NewMessage(mail.SetCharset("ISO-8859-1"))

Output:

func SetEncoding 

func SetEncoding(enc Encoding) MessageSetting

SetEncoding is a message setting to set the encoding of the email.

Example 
m = mail.NewMessage(mail.SetEncoding(mail.Base64))

Output:

type PartSetting 

type PartSetting func(*part)

A PartSetting can be used as an argument in Message.SetBody, Message.SetBodyWriter, Message.AddAlternative or Message.AddAlternativeWriter to configure the part added to a message.

func SetPartEncoding 

func SetPartEncoding(e Encoding) PartSetting

SetPartEncoding sets the encoding of the part added to the message. By default, parts use the same encoding than the message.

Example 
m.SetBody("text/plain", "Hello!", mail.SetPartEncoding(mail.Unencoded))

Output:

type SendCloser 

type SendCloser interface {
	Sender
	Close() error
}

SendCloser is the interface that groups the Send and Close methods.

type SendError 

type SendError struct {
	// Index specifies the index of the Message within a batch.
	Index uint
	Cause error
}

A SendError represents the failure to transmit a Message, detailing the cause of the failure and index of the Message within a batch.

func (*SendError) Error 

func (err *SendError) Error() string

type SendFunc 

type SendFunc func(from string, to []string, msg io.WriterTo) error

A SendFunc is a function that sends emails to the given addresses.

The SendFunc type is an adapter to allow the use of ordinary functions as email senders. If f is a function with the appropriate signature, SendFunc(f) is a Sender object that calls f.

func (SendFunc) Send 

func (f SendFunc) Send(from string, to []string, msg io.WriterTo) error

Send calls f(from, to, msg).

type Sender 

type Sender interface {
	Send(from string, to []string, msg io.WriterTo) error
}

Sender is the interface that wraps the Send method.

Send sends an email to the given addresses.

type ServerInfo 

type ServerInfo struct {
	Name string   // SMTP server name
	TLS  bool     // using TLS, with valid certificate for Name
	Auth []string // advertised authentication mechanisms
}

ServerInfo records information about an SMTP server.

type StartTLSPolicy 

type StartTLSPolicy int

StartTLSPolicy constants are valid values for Dialer.StartTLSPolicy. 

const (
	// OpportunisticStartTLS means that SMTP transactions are encrypted if
	// STARTTLS is supported by the SMTP server. Otherwise, messages are
	// sent in the clear. This is the default setting.
	OpportunisticStartTLS StartTLSPolicy = iota
	// MandatoryStartTLS means that SMTP transactions must be encrypted.
	// SMTP transactions are aborted unless STARTTLS is supported by the
	// SMTP server.
	MandatoryStartTLS
	// NoStartTLS means encryption is disabled and messages are sent in the
	// clear.
	NoStartTLS = -1
)

func (*StartTLSPolicy) String 

func (policy *StartTLSPolicy) String() string

type StartTLSUnsupportedError 

type StartTLSUnsupportedError struct {
	Policy StartTLSPolicy
}

StartTLSUnsupportedError is returned by Dial when connecting to an SMTP server that does not support STARTTLS.

func (StartTLSUnsupportedError) Error 

func (e StartTLSUnsupportedError) Error() string

Source Files

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