chore: add mailtest tool and local config template

cmd/mailtest/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"crypto/tls"
+	"fmt"
+	"log"
+	"net"
+	"net/smtp"
+	"os"
+	"strings"
+	"time"
+)
+
+func main() {
+	smtpHost := getenv("SMTP_HOST", "smtp.163.com")
+	smtpPort := getenv("SMTP_PORT", "465")
+	smtpUser := strings.TrimSpace(os.Getenv("SMTP_USER"))
+	smtpPass := strings.TrimSpace(os.Getenv("SMTP_PASS"))
+	mailTo := strings.TrimSpace(os.Getenv("MAIL_TO"))
+	subject := getenv("MAIL_SUBJECT", "SuperTodo SMTP test")
+	body := getenv("MAIL_BODY", "This is a SMTP connectivity test email from SuperTodo.")
+
+	if smtpUser == "" || smtpPass == "" || mailTo == "" {
+		log.Fatal("missing required env: SMTP_USER, SMTP_PASS, MAIL_TO")
+	}
+
+	if err := sendMailTLS(smtpHost, smtpPort, smtpUser, smtpPass, mailTo, subject, body); err != nil {
+		log.Fatalf("send mail failed: %v", err)
+	}
+
+	log.Printf("mail sent successfully: from=%s to=%s via %s:%s", smtpUser, mailTo, smtpHost, smtpPort)
+}
+
+func sendMailTLS(host, port, user, pass, to, subject, body string) error {
+	addr := net.JoinHostPort(host, port)
+	dialer := &net.Dialer{Timeout: 10 * time.Second}
+	conn, err := tls.DialWithDialer(dialer, "tcp", addr, &tls.Config{
+		ServerName: host,
+		MinVersion: tls.VersionTLS12,
+	})
+	if err != nil {
+		return fmt.Errorf("tls dial failed: %w", err)
+	}
+	defer conn.Close()
+
+	client, err := smtp.NewClient(conn, host)
+	if err != nil {
+		return fmt.Errorf("smtp client failed: %w", err)
+	}
+	defer client.Close()
+
+	auth := smtp.PlainAuth("", user, pass, host)
+	if err := client.Auth(auth); err != nil {
+		return fmt.Errorf("smtp auth failed: %w", err)
+	}
+	if err := client.Mail(user); err != nil {
+		return fmt.Errorf("mail from failed: %w", err)
+	}
+	if err := client.Rcpt(to); err != nil {
+		return fmt.Errorf("rcpt to failed: %w", err)
+	}
+
+	w, err := client.Data()
+	if err != nil {
+		return fmt.Errorf("data failed: %w", err)
+	}
+
+	msg := buildMessage(user, to, subject, body)
+	if _, err := w.Write([]byte(msg)); err != nil {
+		return fmt.Errorf("write message failed: %w", err)
+	}
+	if err := w.Close(); err != nil {
+		return fmt.Errorf("close writer failed: %w", err)
+	}
+	if err := client.Quit(); err != nil {
+		return fmt.Errorf("smtp quit failed: %w", err)
+	}
+	return nil
+}
+
+func buildMessage(from, to, subject, body string) string {
+	var b strings.Builder
+	b.WriteString("From: " + from + "\r\n")
+	b.WriteString("To: " + to + "\r\n")
+	b.WriteString("Subject: " + subject + "\r\n")
+	b.WriteString("MIME-Version: 1.0\r\n")
+	b.WriteString("Content-Type: text/plain; charset=UTF-8\r\n")
+	b.WriteString("\r\n")
+	b.WriteString(body)
+	if !strings.HasSuffix(body, "\n") {
+		b.WriteString("\r\n")
+	}
+	return b.String()
+}
+
+func getenv(key, fallback string) string {
+	v := strings.TrimSpace(os.Getenv(key))
+	if v == "" {
+		return fallback
+	}
+	return v
+}
+