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Published: Mar 3, 2023 License: MulanPSL-2.0 Imports: 24 Imported by: 0



The email package currently supports the following:

  • From, To, Bcc, and Cc fields
  • Email addresses in both "test@example.com" and "First Last <test@example.com>" format
  • Text and HTML Message Body
  • Attachments
  • Read Receipts
  • Custom headers
  • More to come!
Sending email using Gmail
e := email.NewEmail()
e.From = "Jordan Wright <test@gmail.com>"
e.To = []string{"test@example.com"}
e.Bcc = []string{"test_bcc@example.com"}
e.Cc = []string{"test_cc@example.com"}
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.gmail.com:587", smtp.PlainAuth("", "test@gmail.com", "password123", "smtp.gmail.com"))
Another Method for Creating an Email

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

e := &email.Email {
	To: []string{"test@example.com"},
	From: "Jordan Wright <test@gmail.com>",
	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("", "test@gmail.com", "password123", "smtp.gmail.com"),
for i := 0; i < 4; i++ {
	go func() {
		for e := range ch {
			p.Send(e, 10 * time.Second)




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
	ContentType string
	Header      textproto.MIMEHeader
	Content     []byte
	HTMLRelated bool

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 {
	ReplyTo     []string
	From        string
	To          []string
	Bcc         []string
	Cc          []string
	Subject     string
	Text        []byte // Plaintext message (optional)
	HTML        []byte // Html message (optional)
	Sender      string // override From as SMTP envelope sender (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) SendWithStartTLS

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

SendWithStartTLS sends an email over TLS using STARTTLS with an optional TLS config.

The TLS Config is helpful if you need to connect to a host that is used an untrusted certificate.

func (*Email) SendWithTLS

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

SendWithTLS sends an email over tls with an optional TLS config.

The TLS Config 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, opt_tlsConfig ...*tls.Config) (pool *Pool, err error)

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.

func (*Pool) SetHelloHostname

func (p *Pool) SetHelloHostname(h string)

SetHelloHostname optionally sets the hostname that the Go smtp.Client will use when doing a HELLO with the upstream SMTP server. By default, Go uses "localhost" which may not be accepted by certain SMTP servers that demand an FQDN.

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