Conversations
Settings
The mail says which character wrote, never what. One per conversation until you have read it.
Blocked players
They cannot write to you, and you do not see them on Crafters.
You have blocked nobody yet.
About this page: who sees what
Everyone sees you as the character you wrote as, never your email address or BattleTag. A friend is written to on a character their share shows, a guildmate on one their shared guild row shows, a stranger on one their open profile shows.
Anonymous requests from Crafters stay anonymous for the asker until the crafter answers.