The vast majority of messages in my spam folder are not spam on Gmail at the moment. Most of them are from providers I've semi-regularly tried to get it to recognize as not spam for months or years. Of course Gmail also outright rejects a lot of stuff at the SMTP stage, so their filters are better than they look, but the amount of misclassification is extremely frustrating.
I have this issue with OSSEC messages (automated messages from an Open Source IDS). Same thing, too, have been marking them as “not spam” for years. I think it’s because I don’t always review them...:/ But just because you don’t always open a message class doesn’t mean it’s spam, Google!
At one place we even had them start bulk-rejecting messages for our Google Apps domain from a whitelisted source.
The entire point of the whitelisting was to allow our internal mail server to forward transactional messages to addresses on our own domain, so it was not even that it was ever reported as spam by anyone, or ever hitting external addresses where I'd understand if Google was more trigger happy.
It was ridiculous realising that they basically had no way for even paying customers to tell them that "that e-mail server we told you is ours and we always want to receive all e-mail from no matter how spammy you think it is, using the mechanism you say it there to do exactly that, well, we really mean it". Instead it'd randomly just stop working. [this is a few years ago; who knows, maybe they've fixed it]
