Such emails are serious violations of the Answers site rules and guidelines. Please forward all 3 emails, with headers, if possible (to determine origin) to answers-abuse@cc.yahoo-inc.com along with a link to the Q/A which instigated them and a brief explanation, just as you've done here. Customer Care will investigate the abusive emails and, hopefully, take the appropriate action.
Bare in mind, however, that those who have accounts suspended often simply open new accounts, so there is no guarantee that this will be the end of the matter. Also, ones Answers account is separate from ones email account, so this person may continue to send notes to you. Should that happen, please continue to forward any and all such emails to Yahoo for continued action, possibly the lose of his entire account.
There is also another Yahoo email address but I'm unable to locate it at the moment. Should I find it (I'll edit this) or someone else provide it, please so the same for that address.
My additional advice is that in the future, you don't answer such questions. A common trap that all too many members fall into as they don't understand they can get caught in a violation by responding to flamebait questions like these in the wrong way. They then get reported and, often, lose their own accounts. Often, that is the sole goal of the question...to lure you in and slap you down.