feat: add dual-engine email service with aliyun smtp and resend routing

Route Chinese domains (edu.cn, qq.com, 163.com, etc.) via Aliyun SMTP
and international addresses via Resend API.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

config/config.go

@@ -16,6 +16,25 @@ type Config struct {
 	Mathpix   MathpixConfig     `mapstructure:"mathpix"`
 	BaiduOCR  BaiduOCRConfig    `mapstructure:"baidu_ocr"`
 	Google    GoogleOAuthConfig `mapstructure:"google"`
+	Email     EmailConfig       `mapstructure:"email"`
+}
+
+type EmailConfig struct {
+	FromName   string           `mapstructure:"from_name"`
+	FromAddr   string           `mapstructure:"from_addr"`
+	AliyunSMTP AliyunSMTPConfig `mapstructure:"aliyun_smtp"`
+	Resend     ResendEmailConfig `mapstructure:"resend"`
+}
+
+type AliyunSMTPConfig struct {
+	Host     string `mapstructure:"host"`
+	Port     int    `mapstructure:"port"`
+	Username string `mapstructure:"username"`
+	Password string `mapstructure:"password"`
+}
+
+type ResendEmailConfig struct {
+	APIKey string `mapstructure:"api_key"`
 }
 
 type BaiduOCRConfig struct {

config/config_dev.yaml

@@ -56,3 +56,14 @@ google:
   client_secret: "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"
   redirect_uri: "https://app.cloud.texpixel.com:10443/auth/google/callback"
   proxy: "http://localhost:7890"
+
+email:
+  from_name: "TexPixel Support"
+  from_addr: "support@texpixel.com"
+  aliyun_smtp:
+    host: "smtp.qiye.aliyun.com"
+    port: 465
+    username: "support@texpixel.com"
+    password: "8bPw2W9LlgHSTTfk"
+  resend:
+    api_key: "re_xxxxxxxxxxxx"

config/config_prod.yaml

@@ -56,3 +56,14 @@ google:
   client_secret: "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"
   redirect_uri: "https://texpixel.com/auth/google/callback"
   proxy: "http://100.115.184.74:7890"
+
+email:
+  from_name: "TexPixel Support"
+  from_addr: "support@texpixel.com"
+  aliyun_smtp:
+    host: "smtp.qiye.aliyun.com"
+    port: 465
+    username: "support@texpixel.com"
+    password: "8bPw2W9LlgHSTTfk"
+  resend:
+    api_key: "re_xxxxxxxxxxxx"

main.go

@@ -18,6 +18,7 @@ import (
 	"gitea.com/texpixel/document_ai/pkg/cors"
 	"gitea.com/texpixel/document_ai/pkg/log"
 	"gitea.com/texpixel/document_ai/pkg/middleware"
+	"gitea.com/texpixel/document_ai/pkg/email"
 	"gitea.com/texpixel/document_ai/pkg/sms"
 	"github.com/gin-gonic/gin"
 )
@@ -44,6 +45,7 @@ func main() {
 	dao.InitDB(config.GlobalConfig.Database)
 	cache.InitRedisClient(config.GlobalConfig.Redis)
 	sms.InitSmsClient()
+	email.InitEmailClient()
 
 	// 设置gin模式
 	gin.SetMode(config.GlobalConfig.Server.Mode)

pkg/email/email.go

@@ -0,0 +1,154 @@
+package email
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/smtp"
+	"regexp"
+	"sync"
+
+	"gitea.com/texpixel/document_ai/config"
+	"gitea.com/texpixel/document_ai/pkg/log"
+)
+
+var (
+	once   sync.Once
+	client *Client
+)
+
+// chineseDomainRe matches email domains that should be routed via Aliyun SMTP.
+var chineseDomainRe = regexp.MustCompile(`(?i)(\.edu\.cn|qq\.com|163\.com|126\.com|sina\.com|sohu\.com)$`)
+
+type Client struct {
+	cfg config.EmailConfig
+}
+
+func InitEmailClient() *Client {
+	once.Do(func() {
+		client = &Client{cfg: config.GlobalConfig.Email}
+	})
+	return client
+}
+
+// Send routes the email to the appropriate provider based on the recipient domain.
+func Send(ctx context.Context, to, subject, body string) error {
+	return client.Send(ctx, to, subject, body)
+}
+
+func (c *Client) Send(ctx context.Context, to, subject, body string) error {
+	atIdx := len(to) - 1
+	for i, ch := range to {
+		if ch == '@' {
+			atIdx = i
+		}
+	}
+	domain := to[atIdx:]
+	if chineseDomainRe.MatchString(domain) {
+		return c.sendViaAliyunSMTP(ctx, to, subject, body)
+	}
+	return c.sendViaResend(ctx, to, subject, body)
+}
+
+func (c *Client) sendViaAliyunSMTP(ctx context.Context, to, subject, body string) error {
+	cfg := c.cfg.AliyunSMTP
+	addr := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
+
+	tlsConfig := &tls.Config{ServerName: cfg.Host}
+	conn, err := tls.Dial("tcp", addr, tlsConfig)
+	if err != nil {
+		log.Error(ctx, "func", "sendViaAliyunSMTP", "msg", "tls dial failed", "error", err)
+		return err
+	}
+
+	smtpClient, err := smtp.NewClient(conn, cfg.Host)
+	if err != nil {
+		log.Error(ctx, "func", "sendViaAliyunSMTP", "msg", "smtp new client failed", "error", err)
+		return err
+	}
+	defer smtpClient.Close()
+
+	auth := smtp.PlainAuth("", cfg.Username, cfg.Password, cfg.Host)
+	if err = smtpClient.Auth(auth); err != nil {
+		log.Error(ctx, "func", "sendViaAliyunSMTP", "msg", "smtp auth failed", "error", err)
+		return err
+	}
+
+	from := c.cfg.FromAddr
+	if err = smtpClient.Mail(from); err != nil {
+		return err
+	}
+	if err = smtpClient.Rcpt(to); err != nil {
+		return err
+	}
+
+	wc, err := smtpClient.Data()
+	if err != nil {
+		return err
+	}
+	defer wc.Close()
+
+	if _, err = wc.Write([]byte(buildMessage(c.cfg.FromName, from, to, subject, body))); err != nil {
+		return err
+	}
+
+	log.Info(ctx, "func", "sendViaAliyunSMTP", "msg", "email sent via aliyun smtp", "to", to)
+	return nil
+}
+
+type resendRequest struct {
+	From    string   `json:"from"`
+	To      []string `json:"to"`
+	Subject string   `json:"subject"`
+	Html    string   `json:"html"`
+}
+
+func (c *Client) sendViaResend(ctx context.Context, to, subject, body string) error {
+	payload := resendRequest{
+		From:    fmt.Sprintf("%s <%s>", c.cfg.FromName, c.cfg.FromAddr),
+		To:      []string{to},
+		Subject: subject,
+		Html:    body,
+	}
+	jsonData, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://api.resend.com/emails", bytes.NewReader(jsonData))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+c.cfg.Resend.APIKey)
+
+	resp, err := (&http.Client{}).Do(req)
+	if err != nil {
+		log.Error(ctx, "func", "sendViaResend", "msg", "http request failed", "error", err)
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
+		log.Error(ctx, "func", "sendViaResend", "msg", "resend api returned non-2xx", "status", resp.StatusCode, "to", to)
+		return fmt.Errorf("resend api returned status: %d", resp.StatusCode)
+	}
+
+	log.Info(ctx, "func", "sendViaResend", "msg", "email sent via resend", "to", to)
+	return nil
+}
+
+func buildMessage(fromName, fromAddr, to, subject, body string) string {
+	var buf bytes.Buffer
+	buf.WriteString(fmt.Sprintf("From: %s <%s>\r\n", fromName, fromAddr))
+	buf.WriteString(fmt.Sprintf("To: %s\r\n", to))
+	buf.WriteString(fmt.Sprintf("Subject: %s\r\n", subject))
+	buf.WriteString("MIME-Version: 1.0\r\n")
+	buf.WriteString("Content-Type: text/html; charset=UTF-8\r\n")
+	buf.WriteString("\r\n")
+	buf.WriteString(body)
+	return buf.String()
+}