diff --git a/backend/07-migrate.go b/backend/07-migrate.go
index c13c79e..ce491e5 100644
--- a/backend/07-migrate.go
+++ b/backend/07-migrate.go
@@ -124,6 +124,29 @@ func migrateAccount(a Account) error {
 	return nil
 }
 
+func CheckAccount(name string) error {
+	a, err := GetAccount(name)
+	if err != nil {
+		return err
+	}
+	src, err := OpenIMAPSource(a)
+	if err != nil {
+		return fmt.Errorf("open source %s: %w", a.Name, err)
+	}
+	defer src.Close()
+	msgs, err := src.Fetch("INBOX")
+	if err != nil {
+		return fmt.Errorf("fetch source INBOX %s: %w", a.Name, err)
+	}
+	dst, err := OpenIMAPTarget(a)
+	if err != nil {
+		return fmt.Errorf("open target %s: %w", a.Name, err)
+	}
+	defer dst.Close()
+	log.Printf("account %s ok: source INBOX messages=%d, target login ok", a.Name, len(msgs))
+	return nil
+}
+
 func startJob(accountID int64) (int64, error) {
 	res, err := DB.Exec(`INSERT INTO jobs(account_id,state) VALUES(?, 'running')`, accountID)
 	if err != nil {
diff --git a/main.go b/main.go
index 6f5413f..ab38654 100644
--- a/main.go
+++ b/main.go
@@ -18,6 +18,7 @@ func main() {
 	runOnce := flag.String("run", "", "einen Umzugs-Job einmalig ausfuehren (Konto-Name oder 'all'), ohne Web-UI")
 	watch := flag.Bool("watch", false, "Delta-Sync in Schleife bis Stop (Cutover-Fenster)")
 	seedAccount := flag.String("seed-account", "", "Konto aus lokaler JSON-Datei in die DB schreiben (nur CLI/Test)")
+	checkAccount := flag.String("check-account", "", "Konto-Logins pruefen und INBOX zaehlen, ohne zu kopieren")
 	flag.Parse()
 
 	if err := backend.LoadConfig("config.json"); err != nil {
@@ -34,6 +35,10 @@ func main() {
 		must(backend.SeedAccountFromFile(*seedAccount))
 		return
 	}
+	if *checkAccount != "" {
+		must(backend.CheckAccount(*checkAccount))
+		return
+	}
 
 	// CLI-Modus: ohne Web laufen lassen (Cronjob / Cutover).
 	if *runOnce != "" {