In an effort to minimize abuse of the system, some outgoing mailings may need to be reviewed by a compliance administrator. Typically this is done within minutes, however, in some cases (specifically non-business hours) there can be a longer delay. In order to ensure your campaigns do not get held up by the approval process, schedule them in advance before you would like them to be sent. A campaign can be approved as soon as it's submitted, so don't wait until the last minute to schedule them!