I went to postmates.com and saw they supported Boston. Great! So I enter my address, and then get an error message saying they don't support my area, why don't

I went to postmates.com and saw they supported Boston. Great! So I enter my address, and then get an error message saying they don't support my area, why don't I browse their list of current cities - which includes Boston. Is there a map somewhere of the subset of Boston they actually support?