diff --git a/cmd/migrate/main.go b/cmd/migrate/main.go
new file mode 100644
index 0000000..71ce115
--- /dev/null
+++ b/cmd/migrate/main.go
@@ -0,0 +1,215 @@
+// migrate 一次性工具：把 SQLite 数据迁移到 MySQL（mailgo 库）。
+// 用法：go run ./cmd/migrate -from /srv/mail_go/mail.db -dsn "mailgo:密码@tcp(127.0.0.1:3306)/mailgo?charset=utf8mb4&parseTime=True&loc=UTC"
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"time"
+
+	"mail_go/config"
+	"mail_go/internal/db"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+var (
+	fromDSN = flag.String("from", "/srv/mail_go/mail.db", "SQLite 数据库路径")
+	mysqlDSN = flag.String("dsn", "", "MySQL DSN（目标库，需已创建 mailgo 库与用户）")
+)
+
+func main() {
+	flag.Parse()
+	if *mysqlDSN == "" {
+		log.Fatal("缺少 -dsn")
+	}
+
+	// 目标：MySQL（InitDB 内含 AutoMigrate，按当前模型建表）
+	mdb, err := db.InitDB(config.DatabaseConfig{Driver: "mysql", DSN: *mysqlDSN}, config.StorageConfig{BaseDir: "/srv/mail_go/"})
+	if err != nil {
+		log.Fatalf("连接 MySQL 失败: %v", err)
+	}
+	log.Println("MySQL 建表完成（AutoMigrate）")
+
+	// 源：SQLite（只读）
+	sdb, err := db.InitDB(config.DatabaseConfig{Driver: "sqlite", DSN: *fromDSN}, config.StorageConfig{BaseDir: "/srv/mail_go/"})
+	if err != nil {
+		log.Fatalf("连接 SQLite 失败: %v", err)
+	}
+	sdb.Logger = logger.Default.LogMode(logger.Silent)
+
+	// 关闭 GORM 自动时间戳（保留原始 CreatedAt/UpdatedAt）
+	mw := mdb.Session(&gorm.Session{SkipHooks: true})
+
+	// 按外键依赖顺序复制：domains → users → messages → attachments → 其余
+	// 所有时间统一 UTC（MySQL DATETIME 无时区）。
+	utc := func(t time.Time) time.Time {
+		if t.IsZero() {
+			// MySQL DATETIME 最小年份 1000；零值由调用方转 NULL
+			return t
+		}
+		return t.UTC()
+	}
+	_ = utc
+
+	// ---- domains ----
+	var domains []db.Domain
+	if err := sdb.Order("id").Find(&domains).Error; err != nil {
+		log.Fatalf("读 domains: %v", err)
+	}
+	for i := range domains {
+		domains[i].CreatedAt = domains[i].CreatedAt.UTC()
+		domains[i].UpdatedAt = domains[i].UpdatedAt.UTC()
+	}
+	if err := mw.Create(&domains).Error; err != nil {
+		log.Fatalf("写 domains: %v", err)
+	}
+	log.Printf("domains: %d", len(domains))
+
+	// ---- users ----
+	var users []db.User
+	if err := sdb.Order("id").Find(&users).Error; err != nil {
+		log.Fatalf("读 users: %v", err)
+	}
+	for i := range users {
+		users[i].CreatedAt = users[i].CreatedAt.UTC()
+		users[i].UpdatedAt = users[i].UpdatedAt.UTC()
+	}
+	if err := mw.Create(&users).Error; err != nil {
+		log.Fatalf("写 users: %v", err)
+	}
+	log.Printf("users: %d", len(users))
+
+	// ---- messages ----
+	var msgs []db.Message
+	if err := sdb.Order("id").Find(&msgs).Error; err != nil {
+		log.Fatalf("读 messages: %v", err)
+	}
+	for i := range msgs {
+		msgs[i].Date = msgs[i].Date.UTC()
+		msgs[i].CreatedAt = msgs[i].CreatedAt.UTC()
+	}
+	if err := mw.Create(&msgs).Error; err != nil {
+		log.Fatalf("写 messages: %v", err)
+	}
+	log.Printf("messages: %d", len(msgs))
+
+	// ---- attachments ----
+	var atts []db.Attachment
+	if err := sdb.Order("id").Find(&atts).Error; err != nil {
+		log.Fatalf("读 attachments: %v", err)
+	}
+	for i := range atts {
+		atts[i].CreatedAt = atts[i].CreatedAt.UTC()
+	}
+	if err := mw.Create(&atts).Error; err != nil {
+		log.Fatalf("写 attachments: %v", err)
+	}
+	log.Printf("attachments: %d", len(atts))
+
+	// ---- outbound_messages（原样，含时间转 UTC）----
+	var outs []db.OutboundMessage
+	if err := sdb.Order("id").Find(&outs).Error; err != nil {
+		log.Fatalf("读 outbound_messages: %v", err)
+	}
+	for i := range outs {
+		outs[i].NextAttemptAt = outs[i].NextAttemptAt.UTC()
+		if outs[i].CompletedAt != nil && !outs[i].CompletedAt.IsZero() {
+			u := outs[i].CompletedAt.UTC()
+			outs[i].CompletedAt = &u
+		}
+		outs[i].CreatedAt = outs[i].CreatedAt.UTC()
+		outs[i].UpdatedAt = outs[i].UpdatedAt.UTC()
+	}
+	if err := mw.Create(&outs).Error; err != nil {
+		log.Fatalf("写 outbound_messages: %v", err)
+	}
+	log.Printf("outbound_messages: %d", len(outs))
+
+	// ---- ban_entries（expires_at 零值 → NULL）----
+	rows, err := sdb.Raw("SELECT id, ip_address, reason, fail_count, ban_count, expires_at, created_at, updated_at FROM ban_entries ORDER BY id").Rows()
+	if err != nil {
+		log.Fatalf("读 ban_entries: %v", err)
+	}
+	defer rows.Close()
+	bans := 0
+	for rows.Next() {
+		var (
+			id        uint
+			ip        string
+			reason    *string
+			failCount int
+			banCount  int
+			expires   *time.Time
+			created   *time.Time
+			updated   *time.Time
+		)
+		if err := rows.Scan(&id, &ip, &reason, &failCount, &banCount, &expires, &created, &updated); err != nil {
+			log.Fatalf("扫 ban_entries: %v", err)
+		}
+		norm := func(t *time.Time) *time.Time {
+			if t == nil || t.IsZero() {
+				return nil
+			}
+			u := t.UTC()
+			return &u
+		}
+		if err := mdb.Exec("INSERT INTO ban_entries (id, ip_address, reason, fail_count, ban_count, expires_at, created_at, updated_at) VALUES (?,?,?,?,?,?,?,?)",
+			id, ip, reason, failCount, banCount, norm(expires), norm(created), norm(updated)).Error; err != nil {
+			log.Fatalf("写 ban_entries id=%d: %v", id, err)
+		}
+		bans++
+	}
+	log.Printf("ban_entries: %d", bans)
+
+	// ---- protocol_logs ----
+	var logs []db.ProtocolLog
+	if err := sdb.Order("id").Find(&logs).Error; err != nil {
+		log.Fatalf("读 protocol_logs: %v", err)
+	}
+	for i := range logs {
+		logs[i].CreatedAt = logs[i].CreatedAt.UTC()
+	}
+	if err := mw.Create(&logs).Error; err != nil {
+		log.Fatalf("写 protocol_logs: %v", err)
+	}
+	log.Printf("protocol_logs: %d", len(logs))
+
+	// ---- mailbox_states ----
+	var states []db.MailboxState
+	if err := sdb.Order("user_id ASC, folder ASC").Find(&states).Error; err != nil {
+		log.Fatalf("读 mailbox_states: %v", err)
+	}
+	for i := range states {
+		states[i].CreatedAt = states[i].CreatedAt.UTC()
+		states[i].UpdatedAt = states[i].UpdatedAt.UTC()
+	}
+	if err := mw.Create(&states).Error; err != nil {
+		log.Fatalf("写 mailbox_states: %v", err)
+	}
+	log.Printf("mailbox_states: %d", len(states))
+
+	// ---- 校验 ----
+	check := func(table string, want int64) {
+		var got int64
+		if err := mdb.Table(table).Count(&got).Error; err != nil {
+			log.Fatalf("校验 %s: %v", table, err)
+		}
+		if got != want {
+			log.Fatalf("校验 %s 失败: got %d want %d", table, got, want)
+		}
+		fmt.Printf("校验 %s: %d/%d ✓\n", table, got, want)
+	}
+	check("domains", int64(len(domains)))
+	check("users", int64(len(users)))
+	check("messages", int64(len(msgs)))
+	check("attachments", int64(len(atts)))
+	check("outbound_messages", int64(len(outs)))
+	check("ban_entries", int64(bans))
+	check("protocol_logs", int64(len(logs)))
+	check("mailbox_states", int64(len(states)))
+
+	log.Println("迁移完成 ✅")
+}
diff --git a/internal/db/models.go b/internal/db/models.go
index ffc78a4..5a3639f 100644
--- a/internal/db/models.go
+++ b/internal/db/models.go
@@ -60,8 +60,8 @@ type Message struct {
 	ToAddr    string    `gorm:"size:2048;not null" json:"to_addr"`
 	CcAddr    string    `gorm:"size:2048" json:"cc_addr"`
 	Subject   string    `gorm:"size:1024" json:"subject"`
-	TextBody  string    `gorm:"type:text" json:"text_body"`
-	HtmlBody  string    `gorm:"type:text" json:"html_body"`
+	TextBody  string    `gorm:"type:mediumtext" json:"text_body"`
+	HtmlBody  string    `gorm:"type:mediumtext" json:"html_body"`
 	RawData   string    `gorm:"type:mediumtext" json:"raw_data"`
 	IsRead    bool      `gorm:"default:false" json:"is_read"`
 	IsFlagged bool      `gorm:"default:false" json:"is_flagged"`
@@ -155,10 +155,11 @@ func (ProtocolLog) TableName() string {
 }
 
 // Attachment represents a file attached to an email message.
+// 注意：不声明 Message 关联（避免 GORM 外键名 MessageID 与
+// Message.MessageID 字符串字段冲突，导致 AutoMigrate 生成错误外键）。
 type Attachment struct {
 	ID          uint      `gorm:"primaryKey" json:"id"`
 	MessageID   uint      `gorm:"index;not null" json:"message_id"`
-	Message     Message   `gorm:"foreignKey:MessageID" json:"message"`
 	FileName    string    `gorm:"size:255;not null" json:"file_name"`
 	FilePath    string    `gorm:"size:512;not null" json:"file_path"`
 	ContentType string    `gorm:"size:128" json:"content_type"`
diff --git a/migrate b/migrate
new file mode 100755
index 0000000..a4bf07d
Binary files /dev/null and b/migrate differ