Cleanup

.gitignore

@@ -0,0 +1,2 @@
+.idea/
+*_test.go

address.go

@@ -0,0 +1,23 @@
+package nwmail
+
+import "fmt"
+
+type Address struct {
+	Alias   string
+	Address string
+}
+
+func NewAddress(alias, address string) Address {
+	return Address{
+		Alias:   alias,
+		Address: address,
+	}
+}
+
+func (a Address) String() string {
+	if len(a.Alias) > 0 {
+		return fmt.Sprintf("\"%s\" <%s>", a.Alias, a.Address)
+	}
+
+	return a.Address
+}

client.go

@@ -0,0 +1,49 @@
+package nwmail
+
+import (
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net/smtp"
+)
+
+type Client struct {
+	SMTPHostname   string
+	SMTPPort       int
+	PreferSTARTTLS bool
+}
+
+func NewClient(smtpHostname string, smtpPort int, preferSTARTTLS bool) *Client {
+	return &Client{SMTPHostname: smtpHostname, SMTPPort: smtpPort, PreferSTARTTLS: preferSTARTTLS}
+}
+
+func (c Client) SendMail(mail *Mail) error {
+	conn, err := smtp.Dial(fmt.Sprintf("%s:%d", c.SMTPHostname, c.SMTPPort))
+	if err != nil {
+		return err
+	}
+
+	if c.PreferSTARTTLS {
+		if hasStartTLS, _ := conn.Extension("STARTTLS"); hasStartTLS {
+			err = conn.StartTLS(&tls.Config{ServerName: c.SMTPHostname})
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	conn.Mail(mail.sender)
+	for _, recipient := range mail.recipients {
+		conn.Rcpt(recipient)
+	}
+
+	writer, err := conn.Data()
+	if err != nil {
+		return err
+	}
+
+	io.Copy(writer, mail.Buffer())
+	writer.Close()
+
+	return conn.Quit()
+}

go.mod

@@ -0,0 +1,3 @@
+module git.nwestland.com/tools/nwmail
+
+go 1.18

mail.go

@@ -0,0 +1,128 @@
+package nwmail
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"math/rand"
+	"strings"
+	"time"
+)
+
+const (
+	HTMLUTF8      = "text/html; charset=utf-8"
+	PlainTextUTF8 = "text/plain; charset=utf-8"
+)
+
+type Mail struct {
+	sender     string
+	recipients []string
+	headers    map[string]string
+	body       *bytes.Buffer
+}
+
+func NewMail(sender Address) *Mail {
+	m := &Mail{
+		sender:  sender.Address,
+		headers: map[string]string{},
+		body:    new(bytes.Buffer),
+	}
+
+	m.headers["Message-ID"] = m.generateMessageId()
+	m.headers["From"] = sender.String()
+	m.headers["Content-Type"] = PlainTextUTF8 //default, may be overridden
+	return m
+}
+
+func (m *Mail) AddRecipient(recipient Address) {
+	m.recipients = append(m.recipients, recipient.Address)
+	if len(m.headers["To"]) != 0 {
+		m.headers["To"] += ","
+	}
+
+	m.headers["To"] += recipient.String()
+}
+
+func (m *Mail) AddCC(recipient Address) {
+	m.recipients = append(m.recipients, recipient.Address)
+	if len(m.headers["Cc"]) != 0 {
+		m.headers["Cc"] += ","
+	}
+
+	m.headers["Cc"] += recipient.String()
+}
+
+func (m *Mail) AddBCC(recipient Address) {
+	m.recipients = append(m.recipients, recipient.Address)
+	if len(m.headers["Bcc"]) != 0 {
+		m.headers["Bcc"] += ","
+	}
+
+	m.headers["Bcc"] += recipient.String()
+}
+
+func (m *Mail) SetSubject(subject string) {
+	m.headers["Subject"] = subject
+}
+
+func (m *Mail) SetContentType(contentType string) {
+	m.headers["Content-Type"] = contentType
+}
+
+func (m *Mail) SetPriority(priority Priority) {
+	m.headers["Priority"] = priority.String()
+}
+
+func (m *Mail) SetImportant() {
+	m.headers["Importance"] = "high"
+}
+
+func (m *Mail) SetSensitivity(sensitivity Sensitivity) {
+	m.headers["Sensitivity"] = sensitivity.String()
+}
+
+func (m *Mail) SetReplyTo(replyTo Address) {
+	m.headers["Reply-To"] = replyTo.String()
+}
+
+func (m *Mail) SetReadConfirmation(to Address) {
+	m.headers["Disposition-Notification-To"] = to.String()
+}
+
+func (m *Mail) SetReceivedConfirmation(to Address) {
+	m.headers["Return-Receipt-To"] = to.String()
+}
+
+func (m *Mail) Write(p []byte) (n int, err error) {
+	return m.body.Write(p)
+}
+
+func (m *Mail) WriteString(s string) (int, error) {
+	return m.body.WriteString(s)
+}
+
+func (m Mail) Buffer() *bytes.Buffer {
+	mailBuf := new(bytes.Buffer)
+	for key, value := range m.headers {
+		mailBuf.WriteString(fmt.Sprintf("%s: %s\n", key, value))
+	}
+
+	mailBuf.WriteString("\n")
+	io.Copy(mailBuf, m.body)
+	return mailBuf
+}
+
+func (m Mail) String() string {
+	return m.Buffer().String()
+}
+
+func (m Mail) generateMessageId() string {
+	uniqueId := make([]byte, 8)
+	rand.Seed(time.Now().UnixNano())
+	rand.Read(uniqueId)
+
+	host := m.sender[strings.Index(m.sender, "@")+1:]
+
+	return fmt.Sprintf("<%s@%s>", hex.EncodeToString(uniqueId), host)
+}

priority.go

@@ -0,0 +1,17 @@
+package nwmail
+
+type Priority int
+
+const (
+	PriorityUrgent Priority = iota
+	PriorityNormal
+	PriorityNonUrgent
+)
+
+func (p Priority) String() string {
+	return [...]string{
+		"urgent",
+		"normal",
+		"non-urgent",
+	}[p]
+}

sensitivity.go

@@ -0,0 +1,17 @@
+package nwmail
+
+type Sensitivity int
+
+const (
+	SensitivityPersonal Sensitivity = iota
+	SensitivityPrivate
+	SensitivityConfidential
+)
+
+func (s Sensitivity) String() string {
+	return [...]string{
+		"Personal",
+		"Private",
+		"Company-Confidential",
+	}[s]
+}