Can’t Block People in iMessage
Posted February 8th, 2012 @ 09:18am by Erik J. Barzeski
If you search the Intertubes you'll find a few instances of people asking how to block someone from iMessaging them.
Through your carrier, you can block someone from calling and texting you, but Apple has yet to provide a way to prevent a number (or ostensibly an email address) from iMessaging you.
Suppose for instance someone from your past is harassing you. You can block them from calling, and you can block them from texting, but unless you disable iMessage system-wide, you cannot prevent them from iMessaging you.
Apple should add the capability to block iMessages from certain numbers/email addresses.