diff --git a/internal/db/db.go b/internal/db/db.go
index bd489fb..c29fa34 100644
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"mail_go/config"
 
@@ -31,6 +32,15 @@ func InitDB(cfg config.DatabaseConfig, storageCfg config.StorageConfig) (*gorm.D
 		if err := os.MkdirAll(dir, 0755); err != nil {
 			return nil, fmt.Errorf("创建数据库目录失败 %s: %w", dir, err)
 		}
+		// 多连接并发（SMTP/IMAP/POP3/Web/外发 worker/推送）下：
+		// - WAL 模式：读不阻塞写，消除瞬时 SQLITE_BUSY 导致写失败被吞
+		// - busy_timeout=5000ms：写竞争时等待而非立刻失败
+		// - synchronous=NORMAL：WAL 下安全且写入更快
+		sep := "?"
+		if strings.Contains(dsn, "?") {
+			sep = "&"
+		}
+		dsn = dsn + sep + "_busy_timeout=5000&_journal_mode=WAL&_synchronous=NORMAL"
 		dialector = sqlite.Open(dsn)
 	case "mysql":
 		dialector = mysql.Open(cfg.DSN)
diff --git a/internal/imap_server/backend.go b/internal/imap_server/backend.go
index 6a2efcc..15eedea 100644
--- a/internal/imap_server/backend.go
+++ b/internal/imap_server/backend.go
@@ -45,14 +45,14 @@ func (b *imapBackend) Updates() <-chan backend.Update {
 }
 
 // buildNewMessageUpdate 为一条新投递到 mailbox 的邮件构造 IMAP 更新。
-// seq 取该邮件在邮箱中的序号（通知时机在入库之后，取当前列表长度）。
+// seq 取该邮件在邮箱中的实际序号（最新在前，通常为 1）。
 func buildNewMessageUpdate(stores *store.Stores, userEmail, mailbox string, msg *db.Message) *backend.MessageUpdate {
 	if stores == nil || msg == nil || userEmail == "" || mailbox == "" {
 		return nil
 	}
-	seq := uint32(1)
-	if msgs, err := stores.Mails.ListAllByUserAndFolder(msg.UserID, mailbox); err == nil {
-		seq = uint32(len(msgs))
+	seq := seqOf(stores, msg.UserID, mailbox, msg.ID)
+	if seq == 0 {
+		seq = 1
 	}
 
 	imapMsg := imap.NewMessage(seq, []imap.FetchItem{imap.FetchUid, imap.FetchFlags, imap.FetchInternalDate, imap.FetchRFC822Size, imap.FetchEnvelope})
@@ -751,6 +751,10 @@ func (m *imapMailbox) UpdateMessagesFlags(uid bool, seqset *imap.SeqSet, op imap
 		return err
 	}
 
+	// 记录首个持久化错误：SQLite 忙/锁等瞬时失败必须让客户端感知
+	// （返回 NO 触发重试），否则已读/星标会静默丢失。
+	var firstErr error
+
 	for i, dbMsg := range dbMessages {
 		var match bool
 		if uid {
@@ -770,9 +774,15 @@ func (m *imapMailbox) UpdateMessagesFlags(uid bool, seqset *imap.SeqSet, op imap
 		applyFlag := func(flag string, enabled bool) {
 			switch flag {
 			case "\\Seen":
-				_ = m.stores.Mails.MarkReadState(dbMsg.ID, enabled)
+				if err := m.stores.Mails.MarkReadState(dbMsg.ID, enabled); err != nil && firstErr == nil {
+					log.Printf("IMAP: mark read state for msg %d failed: %v", dbMsg.ID, err)
+					firstErr = err
+				}
 			case "\\Flagged":
-				_ = m.stores.Mails.MarkFlagged(dbMsg.ID, enabled)
+				if err := m.stores.Mails.MarkFlagged(dbMsg.ID, enabled); err != nil && firstErr == nil {
+					log.Printf("IMAP: mark flagged for msg %d failed: %v", dbMsg.ID, err)
+					firstErr = err
+				}
 			case "\\Deleted":
 				if enabled {
 					m.deleted[dbMsg.ID] = true
@@ -807,7 +817,7 @@ func (m *imapMailbox) UpdateMessagesFlags(uid bool, seqset *imap.SeqSet, op imap
 		pushUpdate(m.user.updates, buildFlagsUpdate(m.stores, m.user.email, m.name, fresh, deleted))
 	}
 
-	return nil
+	return firstErr
 }
 
 // CopyMessages copies messages to another mailbox.
diff --git a/internal/imap_server/integration_test.go b/internal/imap_server/integration_test.go
new file mode 100644
index 0000000..4b5049f
--- /dev/null
+++ b/internal/imap_server/integration_test.go
@@ -0,0 +1,190 @@
+//go:build !race
+
+// 集成测试：启动真实 IMAP 监听 + 脚本客户端（go-imap client）。
+// 注意：仅在非 -race 构建下运行——go-imap v1.2.1 存在库内数据竞争
+// （cmd_selected.go STORE 写 *conn.silent() vs listenUpdates 读），
+// 启用 backend 推送（Updates != nil）时必然触发，-race 下会误报。
+// 推送逻辑的竞态覆盖由单元测试（notify_test.go）承担。
+package imap_server
+
+import (
+	"net"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"mail_go/config"
+	"mail_go/internal/connhub"
+	"mail_go/internal/db"
+	"mail_go/internal/store"
+
+	"github.com/emersion/go-imap"
+	"github.com/emersion/go-imap/client"
+	"golang.org/x/crypto/bcrypt"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+// startIntegrationServer 启动一个真实的 IMAP 监听（随机端口）供客户端测试。
+func startIntegrationServer(t *testing.T) (*store.Stores, string) {
+	t.Helper()
+	gdb, err := gorm.Open(sqlite.Open(filepath.Join(t.TempDir(), "test.db")), &gorm.Config{})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	if err := gdb.AutoMigrate(&db.User{}, &db.Domain{}, &db.Message{}, &db.ProtocolLog{}, &db.BanEntry{}); err != nil {
+		t.Fatalf("migrate: %v", err)
+	}
+	stores := store.NewStores(gdb)
+
+	domain := &db.Domain{Name: "example.com"}
+	if err := stores.Domains.Create(domain); err != nil {
+		t.Fatalf("create domain: %v", err)
+	}
+	hashed, _ := bcrypt.GenerateFromPassword([]byte("secret123"), bcrypt.DefaultCost)
+	user := &db.User{Username: "alice", DomainID: domain.ID, PasswordHash: string(hashed), IsActive: true}
+	if err := stores.Users.Create(user); err != nil {
+		t.Fatalf("create user: %v", err)
+	}
+
+	srv := NewIMAPServer(config.IMAPConfig{}, stores, nil, config.BanConfig{}, connhub.New())
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	t.Cleanup(func() { ln.Close() })
+
+	imapSrv := srv.newServer(ln.Addr().String(), nil)
+	go imapSrv.Serve(ln)
+
+	return stores, ln.Addr().String()
+}
+
+// seedMailbox 创建 n 封按时间递增的邮件（id 与 date 顺序一致时 id ASC == date ASC）。
+func seedMailbox(t *testing.T, stores *store.Stores, userID uint, n int) []uint {
+	t.Helper()
+	ids := make([]uint, 0, n)
+	base := time.Now().Add(-time.Duration(n) * time.Hour)
+	for i := 0; i < n; i++ {
+		msg := &db.Message{
+			UserID:    userID,
+			Folder:    "INBOX",
+			FromAddr:  "x@y",
+			ToAddr:    "alice@example.com",
+			Subject:   "m",
+			Date:      base.Add(time.Duration(i) * time.Hour), // 时间递增：id 越大日期越新
+			CreatedAt: time.Now(),
+		}
+		if err := stores.Mails.Create(msg); err != nil {
+			t.Fatalf("create message: %v", err)
+		}
+		ids = append(ids, msg.ID)
+	}
+	return ids
+}
+
+func loginAndSelect(t *testing.T, addr string) *client.Client {
+	t.Helper()
+	c, err := client.Dial(addr)
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	t.Cleanup(func() { c.Logout() })
+	if err := c.Login("alice@example.com", "secret123"); err != nil {
+		t.Fatalf("login: %v", err)
+	}
+	if _, err := c.Select("INBOX", false); err != nil {
+		t.Fatalf("select: %v", err)
+	}
+	return c
+}
+
+// uidOf returns the message id of the newest message by date.
+func assertReadState(t *testing.T, stores *store.Stores, msgID uint, want bool) {
+	t.Helper()
+	msg, err := stores.Mails.GetByID(msgID)
+	if err != nil {
+		t.Fatalf("get msg: %v", err)
+	}
+	if msg.IsRead != want {
+		t.Fatalf("msg %d IsRead = %v, want %v", msgID, msg.IsRead, want)
+	}
+}
+
+// TestUidStorePersists 验证 UID STORE +FLAGS(\Seen) 持久化（RFC 标准流程）。
+func TestUidStorePersists(t *testing.T) {
+	stores, addr := startIntegrationServer(t)
+	ids := seedMailbox(t, stores, 1, 3)
+
+	c := loginAndSelect(t, addr)
+	seqset := new(imap.SeqSet)
+	seqset.AddNum(uint32(ids[1])) // UID = 第二条消息
+	ch := make(chan *imap.Message, 1)
+	if err := c.UidStore(seqset, imap.AddFlags, []interface{}{imap.SeenFlag}, ch); err != nil {
+		t.Fatalf("uid store: %v", err)
+	}
+	<-ch
+
+	assertReadState(t, stores, ids[1], true)
+	assertReadState(t, stores, ids[0], false)
+	assertReadState(t, stores, ids[2], false)
+}
+
+// TestSeqStoreServerIssued 验证客户端用服务器下发的序号（FETCH 结果）做
+// seq 式 STORE：任何排序下都应正确持久化。
+func TestSeqStoreServerIssued(t *testing.T) {
+	stores, addr := startIntegrationServer(t)
+	ids := seedMailbox(t, stores, 1, 3)
+
+	c := loginAndSelect(t, addr)
+
+	// 拉取全部消息，找到 ids[2]（最新一封）的服务器序号
+	seqsetAll := new(imap.SeqSet)
+	seqsetAll.AddRange(1, 3)
+	messages := make(chan *imap.Message, 3)
+	if err := c.Fetch(seqsetAll, []imap.FetchItem{imap.FetchFlags, imap.FetchUid}, messages); err != nil {
+		t.Fatalf("fetch: %v", err)
+	}
+	var targetSeq uint32
+	for m := range messages {
+		if m.Uid == uint32(ids[2]) {
+			targetSeq = m.SeqNum
+		}
+	}
+	if targetSeq == 0 {
+		t.Fatal("target message not found in fetch")
+	}
+
+	seqset := new(imap.SeqSet)
+	seqset.AddNum(targetSeq)
+	ch := make(chan *imap.Message, 1)
+	if err := c.Store(seqset, imap.AddFlags, []interface{}{imap.SeenFlag}, ch); err != nil {
+		t.Fatalf("store: %v", err)
+	}
+	<-ch
+
+	assertReadState(t, stores, ids[2], true)
+}
+
+// TestSeqStoreClientSelfNumbered 复现风险场景：客户端不信任服务器序号，
+// 按自己的视图（日期倒序，最新在前）自行编号后发 seq 式 STORE。
+// 服务器规范排序必须与常见客户端视图一致（date DESC, id DESC），
+// 否则会把另一封邮件标为已读、目标邮件永远未读。
+func TestSeqStoreClientSelfNumbered(t *testing.T) {
+	stores, addr := startIntegrationServer(t)
+	ids := seedMailbox(t, stores, 1, 3) // 3 封，日期递增，最新的是 ids[2]
+
+	c := loginAndSelect(t, addr)
+
+	// 客户端按日期倒序视图：最新一封 = seq 1
+	seqset := new(imap.SeqSet)
+	seqset.AddNum(1)
+	ch := make(chan *imap.Message, 1)
+	if err := c.Store(seqset, imap.AddFlags, []interface{}{imap.SeenFlag}, ch); err != nil {
+		t.Fatalf("store: %v", err)
+	}
+	<-ch
+
+	// 客户端意图是标记最新一封（ids[2]）为已读
+	assertReadState(t, stores, ids[2], true)
+}
diff --git a/internal/imap_server/notify_test.go b/internal/imap_server/notify_test.go
index 8d32df5..e9aa374 100644
--- a/internal/imap_server/notify_test.go
+++ b/internal/imap_server/notify_test.go
@@ -36,8 +36,8 @@ func TestPushNewMessage(t *testing.T) {
 	}
 	email := "alice@example.com"
 
-	// 已有一封旧邮件，新邮件应为 INBOX 第 2 封
-	old := &db.Message{UserID: user.ID, Folder: "INBOX", FromAddr: "x@y", Subject: "old", Date: time.Now()}
+	// 已有一封旧邮件（日期更早）；规范排序最新在前，新邮件应为 INBOX 第 1 封
+	old := &db.Message{UserID: user.ID, Folder: "INBOX", FromAddr: "x@y", Subject: "old", Date: time.Now().Add(-time.Hour)}
 	if err := stores.Mails.Create(old); err != nil {
 		t.Fatalf("create old message: %v", err)
 	}
@@ -87,8 +87,8 @@ func TestPushNewMessage(t *testing.T) {
 			if mu.Message.Uid != uint32(inboxMsg.ID) {
 				t.Fatalf("backend %d: uid = %d, want %d", i, mu.Message.Uid, inboxMsg.ID)
 			}
-			if mu.Message.SeqNum != 2 {
-				t.Fatalf("backend %d: seq = %d, want 2", i, mu.Message.SeqNum)
+			if mu.Message.SeqNum != 1 {
+				t.Fatalf("backend %d: seq = %d, want 1", i, mu.Message.SeqNum)
 			}
 			if mu.Message.Envelope == nil || mu.Message.Envelope.Subject != "新邮件" {
 				t.Fatalf("backend %d: envelope missing subject", i)
diff --git a/internal/store/mail_store.go b/internal/store/mail_store.go
index 315fec1..554ac74 100644
--- a/internal/store/mail_store.go
+++ b/internal/store/mail_store.go
@@ -118,11 +118,14 @@ func (s *mailStoreGorm) CountUnread(userID uint, folder string) (int64, error) {
 }
 
 // ListAllByUserAndFolder retrieves all messages for a user in a folder without pagination.
-// Messages are ordered by ID ascending so that sequence numbers are stable.
+// 按 date DESC, id DESC 排序（最新在前）：与主流邮件客户端（Thunderbird、
+// 手机客户端等）默认视图一致，客户端自行按日期编号的 seq 式 STORE 不会
+// 错位标错邮件。所有 IMAP 序号相关路径（Status/ListMessages/推送/seqOf）
+// 共用本排序，保证序号全链路一致。
 func (s *mailStoreGorm) ListAllByUserAndFolder(userID uint, folder string) ([]db.Message, error) {
 	var messages []db.Message
 	if err := s.db.Where("user_id = ? AND folder = ?", userID, folder).
-		Order("id ASC").Find(&messages).Error; err != nil {
+		Order("date DESC, id DESC").Find(&messages).Error; err != nil {
 		return nil, err
 	}
 	return messages, nil
diff --git a/internal/web/handlers/mail.go b/internal/web/handlers/mail.go
index f95c12f..8637128 100644
--- a/internal/web/handlers/mail.go
+++ b/internal/web/handlers/mail.go
@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io"
+	"log"
 	"mime"
 	"net/http"
 	"path/filepath"
@@ -132,7 +133,9 @@ func (h *MailHandler) View(c *gin.Context) {
 
 	// Auto mark as read
 	if !msg.IsRead {
-		_ = h.stores.Mails.MarkRead(uint(id))
+		if err := h.stores.Mails.MarkRead(uint(id)); err != nil {
+			log.Printf("web: 标记已读失败 msg=%d: %v", id, err)
+		}
 		msg.IsRead = true
 	}
 
@@ -637,7 +640,9 @@ func (h *MailHandler) Delete(c *gin.Context) {
 		_ = h.storage.Delete(att.FilePath)
 		_ = h.stores.Users.UpdateUsedBytes(userID, -att.FileSize)
 	}
-	_ = h.stores.Attachments.DeleteByMessage(uint(id))
+	if err := h.stores.Attachments.DeleteByMessage(uint(id)); err != nil {
+		log.Printf("web: 删除附件记录失败 msg=%d: %v", id, err)
+	}
 
 	// 删除前计算消息在所属文件夹中的序号（用于 Expunge 推送）
 	var seq uint32
@@ -649,7 +654,9 @@ func (h *MailHandler) Delete(c *gin.Context) {
 			}
 		}
 	}
-	_ = h.stores.Mails.Delete(uint(id))
+	if err := h.stores.Mails.Delete(uint(id)); err != nil {
+		log.Printf("web: 删除邮件失败 msg=%d: %v", id, err)
+	}
 
 	// 删除 → 推送给该用户的其他 IMAP 客户端
 	if h.pusher != nil && seq > 0 {