有效提升邮件发送品质！不可不知的错误代码列表

代码 回应文字 错误理由 421,”4.4.5” Server busy, try again later. 收件人的服务器忙碌中。 421,”4.7.0” IP not in whitelist for RCPT domain, closing connection. IP 位址不在收件人的白名单内。 421,”4.7.0” “Our system has detected an unusual rate of unsolicited mail originating from your IP address.To protect our users from spam, mail sent from your IP address has been temporarily blocked.” 因发信者的 IP 位址发出大量的垃圾邮件，将其暂时封锁。 421,”4.7.0” Temporary System Problem. Try again later 系统的暂时性问题，请稍后再试。 421,”4.7.0” TLS required for RCPT domain, closing connection. 由于邮件未加密，收件端要求设定 TLS（邮件加密）。 450,“4.1.1” Recipient address rejected. unverified address: 收件人的电子邮件地址未认证而被拒绝。 450,”4.2.1” “The user you are trying to contact is receiving mail too quickly.Please resend your message at a later time.If the user is able to receive mail at that time, your message will be delivered.” 发送电子邮件时间间隔太短。 一定时间内有限制能够接收的信件量，且当发送的电子信件超过限制数量时，电子邮件可能会被拒绝接收。而为了避免发生这种状况，延迟电子邮件的发送时间的动作称为「节流」，因此才能稳定地发送电子邮件。） 451,”4.3.0” Mail server temporarily rejected message. 电子邮件服务器暂时拒绝接收邮件。 451,”4.4.2” Timeout – closing connection. 作业逾时。 452,”4.2.2” The email account that you tried to reach is over quota. 收件人的电子邮件容量已满。