The access control mechanisms discussed previously can also defer the processing of suspect messages for later, manual inspection. Or, rather than sideline, the mechanisms can change the destination address, thus routing the suspect mail to a specific mailbox or simply deleting it silently. This tactic is useful when UBE is being received from a known, fixed origin and outright rejection will only cause the abuser to change the point of origin. Similar features are available for Messaging Server mailing lists. Great care should exercised when silently deleting mail to ensure that valid senders are not affected.