当在邮箱服务比如说 Gmail 中分析验证失败的邮件的头域时，有时候会看到如下的错误信息：
Received-SPF: softfail (google.com: domain of transitioning account@domain.com does not designate some IP address as permitted sender)这个 SPF softfail domain does not designate IP as permitted sender 错误信息表明邮件发送者的 IP 地址并没有在发送域名的 SPF 记录中指定，因此 SPF 检查失…
