Your comment motivated me to check my Gmail spam folder and 10% (3 out of 30) were false positives, two of which were pretty important. :(
You'd think the various governments would put more effort into computer security. They appear not to care, though.
Edit: Gah. Now I checked my work Gmail spam folder. There was an email from one of my users there. (and nothing else)
Now I'm considering migrating away from Gmail, at least for work related things.