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Version: v0.0.0-...-30de9e4 Latest Latest

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Published: Nov 7, 2016 License: MIT Imports: 24 Imported by: 0



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Robust and flexible email library for Go

Email for humans

The email package is designed to be simple to use, but flexible enough so as not to be restrictive. The goal is to provide an email interface for humans.

The email package currently supports the following:

  • From, To, Bcc, and Cc fields
  • Email addresses in both "" and "First Last <>" format
  • Text and HTML Message Body
  • Attachments
  • Read Receipts
  • Custom headers
  • More to come!

go get

Note: Version > 1 of this library requires Go v1.5 or above.

If you need compatibility with previous Go versions, you can use the previous package at

Sending email using Gmail
e := email.NewEmail()
e.From = "Jordan Wright <>"
e.To = []string{""}
e.Bcc = []string{""}
e.Cc = []string{""}
e.Subject = "Awesome Subject"
e.Text = []byte("Text Body is, of course, supported!")
e.HTML = []byte("<h1>Fancy HTML is supported, too!</h1>")
e.Send("", smtp.PlainAuth("", "", "password123", ""))
Another Method for Creating an Email

You can also create an email directly by creating a struct as follows:

e := &email.Email {
	To: []string{""},
	From: "Jordan Wright <>",
	Subject: "Awesome Subject",
	Text: []byte("Text Body is, of course, supported!"),
	HTML: []byte("<h1>Fancy HTML is supported, too!</h1>"),
	Headers: textproto.MIMEHeader{},
Creating an Email From an io.Reader

You can also create an email from any type that implements the io.Reader interface by using email.NewEmailFromReader.

Attaching a File
e := NewEmail()
A Pool of Reusable Connections
(var ch <-chan *email.Email)
p := email.NewPool(
	smtp.PlainAuth("", "", "password123", ""),
for i := 0; i < 4; i++ {
	go func() {
		for e := range ch {
			p.Send(e, 10 * time.Second)

Other Sources

Sections inspired by the handy gophermail project.


I'd like to thank all the contributors and maintainers of this package.

A special thanks goes out to Jed Denlea jeddenlea for his numerous contributions and optimizations.



Package email is designed to provide an "email interface for humans." Designed to be robust and flexible, the email package aims to make sending email easy without getting in the way.



View Source
const (
	MaxLineLength = 76 // MaxLineLength is the maximum line length per RFC 2045



View Source
var (
	ErrClosed  = errors.New("pool closed")
	ErrTimeout = errors.New("timed out")
View Source
var ErrMissingBoundary = errors.New("No boundary found for multipart entity")

ErrMissingBoundary is returned when there is no boundary given for a multipart entity

View Source
var ErrMissingContentType = errors.New("No Content-Type found for MIME entity")

ErrMissingContentType is returned when there is no "Content-Type" header for a MIME entity


This section is empty.


type Attachment

type Attachment struct {
	Filename string
	Header   textproto.MIMEHeader
	Content  []byte

Attachment is a struct representing an email attachment. Based on the mime/multipart.FileHeader struct, Attachment contains the name, MIMEHeader, and content of the attachment in question

type Email

type Email struct {
	From        string
	To          []string
	Bcc         []string
	Cc          []string
	Subject     string
	Text        []byte // Plaintext message (optional)
	HTML        []byte // Html message (optional)
	Headers     textproto.MIMEHeader
	Attachments []*Attachment
	ReadReceipt []string

Email is the type used for email messages

func NewEmail

func NewEmail() *Email

NewEmail creates an Email, and returns the pointer to it.

func NewEmailFromReader

func NewEmailFromReader(r io.Reader) (*Email, error)

NewEmailFromReader reads a stream of bytes from an io.Reader, r, and returns an email struct containing the parsed data. This function expects the data in RFC 5322 format.

func (*Email) Attach

func (e *Email) Attach(r io.Reader, filename string, c string) (a *Attachment, err error)

Attach is used to attach content from an io.Reader to the email. Required parameters include an io.Reader, the desired filename for the attachment, and the Content-Type The function will return the created Attachment for reference, as well as nil for the error, if successful.

func (*Email) AttachFile

func (e *Email) AttachFile(filename string) (a *Attachment, err error)

AttachFile is used to attach content to the email. It attempts to open the file referenced by filename and, if successful, creates an Attachment. This Attachment is then appended to the slice of Email.Attachments. The function will then return the Attachment for reference, as well as nil for the error, if successful.

func (*Email) Bytes

func (e *Email) Bytes() ([]byte, error)

Bytes converts the Email object to a []byte representation, including all needed MIMEHeaders, boundaries, etc.

func (*Email) Send

func (e *Email) Send(addr string, a smtp.Auth) error

Send an email using the given host and SMTP auth (optional), returns any error thrown by smtp.SendMail This function merges the To, Cc, and Bcc fields and calls the smtp.SendMail function using the Email.Bytes() output as the message

func (*Email) SendWithTLS

func (e *Email) SendWithTLS(addr string, a smtp.Auth, t *tls.Config) error

SendWithTLS sends an email with an optional TLS config. This is helpful if you need to connect to a host that is used an untrusted certificate.

type Pool

type Pool struct {
	// contains filtered or unexported fields

func NewPool

func NewPool(address string, count int, auth smtp.Auth) *Pool

func (*Pool) Close

func (p *Pool) Close()

Close immediately changes the pool's state so no new connections will be created, then gets and closes the existing ones as they become available.

func (*Pool) Send

func (p *Pool) Send(e *Email, timeout time.Duration) (err error)

Send sends an email via a connection pulled from the Pool. The timeout may be <0 to indicate no timeout. Otherwise reaching the timeout will produce and error building a connection that occurred while we were waiting, or otherwise ErrTimeout.

Source Files

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