According to the eula is it permitted?
Can the email of the account be transferred to a new one?
One can retrieve the new password with that email.
One must look into those....
The sale of basically any MMORPG account (okay 98% of them) is not permitted. Just try 3rd party gold sellers.
Yes, the email can be changed.
However, the account (just like any game account) can be reset/retrieved by the seller by simply saying he forgot his password to his account and email or lost email access, or even say he got hacked. Bottom line, he can use any excuse in the book to get it back.
How you ask? Simple. He emails support with his excuse, along with the games serial key, original signup information like: first/last name on account (which in D3
cannot be changed) original email, original mailing address and possibly more depending on how strict they are.