Follow up: just done the quest lvl 5 and it didn't do sh!t, as i expected.
My character has been created 6 hours ago, and i still cannot receive mails on him.
Please note that this is a pretty important problem, as it made me lose 5kk+ trunks dogi, now of course it's in alpha but what if it happened in beta ?
It seems that it needs a waiting of about 24 hours, as i managed to mail another "new" char that i made 27 hours ago.