The antonyms for the phrase "sends forward" are "holds back," "restrains," "withholds," "pulls back," "stops," and "blocks." When someone sends a message or a plan forward, they are pushing it towards completion or implementation. However, if someone chooses to hold back or withhold their actions, they are not ready to move forward or to allow the process to continue. Restraining or pulling back inhibits the progress and sends the message that the process needs to slow down or stop altogether. Blocking or stopping the forward movement serves as a clear message of disapproval or disagreement, indicating that the suggested action or plan is not viable or appropriate.