The most problematic point in the core Sender ID specification is its recommendation to interpret v=spf1 policies like spf2.0/mfrom,pra instead of spf2.0/mfrom.
最大的问题是，核心Sender ID规范推荐解释v=spf1策略为如同spf2.0/mfrom,pra而不是spf2.0/mfrom。