Лямбда зонд или датчик кислорода

There is no single spam score, because filtering happens in layers.

First the connection and the sending IP. Then authentication with SPF, DKIM and DMARC. Then the sender's reputation built from past mail. Content analysis comes last and matters less than most people think. And providers weigh these layers differently.

uChecker goes through how mailbox providers decide between inbox and spam one layer at a time.