Meanwhile the spam filter at gmail (business account) regularly marks email messages that I send from our own systems (say showing disk space) to our own accounts (and nowhere else) as spam. Also sales lead forms. So they come in and we say 'not spam' and the filter is not smart enough to understand the next very similar email is also not a spam. A human could quite easily see by just the format and the layout (in addition to numerous times marking 'not spam') that it was the not spam.