func sendMail(to []string, cc []string, bcc []string, msg *Message) error {
from := Config.DefaultFrom
server := Config.MailServer
if msg.Server != "" {
server = msg.Server
}
if msg.From != "" {
from = msg.From
}
if from == "" {
return errNoFrom
}
var auth smtp.Auth
cram, username, password, server := parseServer(server)
if username != "" || password != "" {
if cram {
auth = smtp.CRAMMD5Auth(username, password)
} else {
auth = smtp.PlainAuth("", username, password, server)
}
}
var buf bytes.Buffer
headers := msg.Headers
if headers == nil {
headers = make(Headers)
}
if msg.Subject != "" {
headers["Subject"] = msg.Subject
}
headers["From"] = from
if msg.ReplyTo != "" {
headers["Reply-To"] = msg.ReplyTo
}
var err error
if len(to) > 0 {
headers["To"], err = joinAddrs(to)
if err != nil {
return err
}
for ii, v := range to {
if v == Admin {
if Config.AdminEmail == "" {
return errNoAdminEmail
}
to[ii] = Config.AdminEmail
}
}
}
if len(cc) > 0 {
headers["Cc"], err = joinAddrs(cc)
if err != nil {
return err
}
}
if len(bcc) > 0 {
headers["Bcc"], err = joinAddrs(bcc)
if err != nil {
return err
}
}
hk := make([]string, 0, len(headers))
for k := range headers {
hk = append(hk, k)
}
sort.Strings(hk)
for _, k := range hk {
buf.WriteString(fmt.Sprintf("%s: %s\r\n", k, headers[k]))
}
buf.WriteString("MIME-Version: 1.0\r\n")
mw := multipart.NewWriter(&buf)
mw.SetBoundary(makeBoundary())
// Create a multipart mixed first
fmt.Fprintf(&buf, "Content-Type: multipart/mixed;\r\n\tboundary=%q\r\n\r\n", mw.Boundary())
var bodyWriter *multipart.Writer
if msg.TextBody != "" && msg.HTMLBody != "" {
boundary := makeBoundary()
outerHeader := make(textproto.MIMEHeader)
// First part is a multipart/alternative, which contains the text and html bodies
outerHeader.Set("Content-Type", fmt.Sprintf("multipart/alternative; boundary=%q", boundary))
iw, err := mw.CreatePart(outerHeader)
if err != nil {
return err
}
bodyWriter = multipart.NewWriter(iw)
bodyWriter.SetBoundary(boundary)
} else {
bodyWriter = mw
}
if msg.TextBody != "" {
textHeader := make(textproto.MIMEHeader)
textHeader.Set("Content-Type", "text/plain; charset=UTF-8")
tpw, err := bodyWriter.CreatePart(textHeader)
if err != nil {
return err
}
if _, err := io.WriteString(tpw, msg.TextBody); err != nil {
return err
}
tpw.Write(crlf)
tpw.Write(crlf)
}
attached := make(map[*Attachment]bool)
if msg.HTMLBody != "" {
var htmlAttachments []*Attachment
for _, v := range msg.Attachments {
if v.ContentID != "" && strings.Contains(msg.HTMLBody, fmt.Sprintf("cid:%s", v.ContentID)) {
htmlAttachments = append(htmlAttachments, v)
attached[v] = true
}
}
var htmlWriter *multipart.Writer
if len(htmlAttachments) > 0 {
relatedHeader := make(textproto.MIMEHeader)
relatedBoundary := makeBoundary()
relatedHeader.Set("Content-Type", fmt.Sprintf("multipart/related; boundary=%q; type=\"text/html\"", relatedBoundary))
rw, err := bodyWriter.CreatePart(relatedHeader)
if err != nil {
return err
}
htmlWriter = multipart.NewWriter(rw)
htmlWriter.SetBoundary(relatedBoundary)
} else {
htmlWriter = bodyWriter
}
htmlHeader := make(textproto.MIMEHeader)
htmlHeader.Set("Content-Type", "text/html; charset=UTF-8")
thw, err := htmlWriter.CreatePart(htmlHeader)
if err != nil {
return err
}
if _, err := io.WriteString(thw, msg.HTMLBody); err != nil {
return err
}
thw.Write(crlf)
thw.Write(crlf)
for _, v := range htmlAttachments {
attachmentHeader := make(textproto.MIMEHeader)
attachmentHeader.Set("Content-Disposition", "inline")
attachmentHeader.Set("Content-Id", fmt.Sprintf("<%s>", v.ContentID))
attachmentHeader.Set("Content-Transfer-Encoding", "base64")
attachmentHeader.Set("Content-Type", v.ContentType)
aw, err := htmlWriter.CreatePart(attachmentHeader)
if err != nil {
return err
}
b := make([]byte, base64.StdEncoding.EncodedLen(len(v.Data)))
base64.StdEncoding.Encode(b, v.Data)
aw.Write(b)
}
if htmlWriter != bodyWriter {
if err := htmlWriter.Close(); err != nil {
return err
}
}
}
if bodyWriter != mw {
if err := bodyWriter.Close(); err != nil {
return err
}
}
for _, v := range msg.Attachments {
if attached[v] {
continue
}
attachmentHeader := make(textproto.MIMEHeader)
attachmentHeader.Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", v.Name))
attachmentHeader.Set("Content-Transfer-Encoding", "base64")
attachmentHeader.Set("Content-Type", v.ContentType)
aw, err := mw.CreatePart(attachmentHeader)
if err != nil {
return err
}
b := make([]byte, base64.StdEncoding.EncodedLen(len(v.Data)))
base64.StdEncoding.Encode(b, v.Data)
aw.Write(b)
}
if err := mw.Close(); err != nil {
return err
}
if server == "echo" {
printer(buf.String())
return nil
}
return smtp.SendMail(server, auth, from, to, buf.Bytes())
}