wait for email client to complete on shutdown

server/core/internal/email/email.go

@@ -345,7 +345,11 @@ type client interface {
 
 // Close waits for the deliveries still in flight and releases the sender.
 func (s *Sender) Close() error {
-	s.supv.CloseAndWait()
+	// the deliveries must finish on a live context, so the wait precedes
+	// the cancellation Close brings. No new sends can arrive here — the
+	// HTTP server shuts down first — and _sendTimeout bounds the wait.
+	s.supv.Wait()
+	s.supv.Close()
 
 	return nil
 }

server/core/internal/email/email_test.go

@@ -338,6 +338,30 @@ func Test_Sender_SendAccountExists(t *testing.T) {
 	assert.Contains(t, msgBody(t, msg), "https://example.com/login")
 }
 
+func Test_Sender_Close(t *testing.T) {
+	t.Parallel()
+
+	var ctxErr error
+
+	client := &clientMock{
+		DialAndSendWithContextFunc: func(ctx context.Context, _ ...*mail.Msg) error {
+			ctxErr = ctx.Err()
+
+			return nil
+		},
+	}
+	s := stubSender(client)
+
+	s.SendPasswordReset("user@example.com", "https://example.com/reset")
+
+	require.NoError(t, s.Close())
+
+	// Close must drain the in-flight delivery before cancelling the
+	// supervisor context, so the send observed a live context.
+	require.Len(t, client.DialAndSendWithContextCalls(), 1)
+	assert.NoError(t, ctxErr)
+}
+
 // stubSender creates a sender backed by the provided mocked client.
 func stubSender(client *clientMock) *Sender {
 	return &Sender{