这次退回是发送到发送域的DNS记录中的邮件服务器还是发送回发送邮件的邮件服务器的IP地址？
Return-Path: <git-owner@vger.kernel.org> From: Sun He <sunheehnus@gmail.com> To: git@vger.kernel.org Subject: [PATCH v2] Replace memcpy with hashcpy when dealing hash copy globally
