smtp/policy: Store messages with full naming for #33

- Added some tests to make sure stores do not enforce their own naming.
- Improve recipient structured logging.

pkg/message/manager.go

@@ -65,6 +65,7 @@ func (s *StoreManager) Deliver(
 			toaddr[i] = &torecip.Address
 		}
 	}
+	log.Debug().Str("module", "message").Str("mailbox", to.Mailbox).Msg("Delivering message")
 	delivery := &Delivery{
 		Meta: Metadata{
 			Mailbox: to.Mailbox,