Oddly the lack of a decent spam-filter was the reason I left gmail. It had way too many false positives for me, including some very problematic ones. The last straw was when it flagged an email from my landlord as spam, with the explanation that it was flagged because it was written in Danish, a language I don't normally communicate in. It's true that I don't normally write in Danish. But I do live in Denmark, so it doesn't seem very justified to flag something as spam just because it's written in Danish. If anything, emails written in Danish are the most likely to be important!
I've had the opposite experience - demos of hosting mail elsewhere lead to me getting absolutely overwhelmed by spam. I think being a gmail user since it was initially released has given it a really long time to train to the spam I normally receive.
Very few false positives too. Maybe one or two a month.
One or two false positives a month? You must have low standards. <1 false positives a year is my threshold. I don't believe that throwing out non-spam emails is acceptable.
