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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 is versioned using so I promise there will never be backward incompatible changes within each version.

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


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



go get


See the examples in the documentation.


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 (


func main() {
    d := gomail.NewDialer("", 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.


Contributions are more than welcome! See for more info.

Change log





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

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

    More info on Github:

    Example (Daemon)

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

      Example (Newsletter)

        Efficiently send a customized newsletter to a list of recipients.

        Example (NoAuth)

          Send an email using a local SMTP server.

          Example (NoSMTP)

            Send an email using an API or postfix.

            To: []




            This section is empty.


            This section is empty.


            func Send

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

              Send sends emails using the given Sender.


              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 smtp.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
              	// TSLConfig represents the TLS configuration used for the TLS (when the
              	// STARTTLS extension is used) or SSL connection.
              	TLSConfig *tls.Config
              	// LocalName is the hostname sent to the SMTP server with the HELO command.
              	// By default, "localhost" is sent.
              	LocalName string

                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

                  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.


                              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.


                                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.


                                  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


                                        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.


                                          func (*Message) Attach

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

                                            Attach attaches the files to the email.


                                            func (*Message) Embed

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

                                              Embed 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.


                                                func (*Message) FormatDate

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

                                                  FormatDate formats a date as a valid RFC 5322 date.


                                                  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.


                                                        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, AddAlternative or AddAlternativeWriter.


                                                          func (*Message) SetDateHeader

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

                                                            SetDateHeader sets a date to the given header field.


                                                            func (*Message) SetHeader

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

                                                              SetHeader sets a value to the given header field.


                                                              func (*Message) SetHeaders

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

                                                                SetHeaders sets the message headers.


                                                                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.


                                                                      func SetEncoding

                                                                      func SetEncoding(enc Encoding) MessageSetting

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


                                                                        type PartSetting

                                                                        type PartSetting func(*part)

                                                                          A PartSetting can be used as an argument in Message.SetBody, 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.


                                                                            type SendCloser

                                                                            type SendCloser interface {
                                                                            	Close() error

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

                                                                              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.