It's spam for two reasons: 1) The default setting for a long time (not sure about now) was that you'd get an email every time someone new followed you. 2) For

It's spam for two reasons: 1) The default setting for a long time (not sure about now) was that you'd get an email every time someone new followed you. 2) For those folks looking to make actual social connections on Twitter, it's next to impossible to notice when someone actually interesting starts following you-- the signal-to-noise on the followers lists means that it'll get drowned out. I've had some really interesting leads go stale as a result of this.