diff --git a/smtp/auth_login.go b/smtp/auth_login.go
index e25b3e6..715861c 100644
--- a/smtp/auth_login.go
+++ b/smtp/auth_login.go
@@ -57,6 +57,7 @@ func (a *loginAuth) Start(server *ServerInfo) (string, []byte, error) {
 	if server.Name != a.host {
 		return "", nil, errors.New("wrong host name")
 	}
+	a.respStep = 0
 	return "LOGIN", nil, nil
 }