PhPBB, the forum software of lemon site, needs your old email to reset
password.
BTW, Lemon is a strange site. It seems to be without the possibility of contact
from an outsider.
You can register a new account and, from this, write to one of the
administrators or to all the administrators to have the password of the old
account reset. Naturally you will have to provide proof that you are actually
the holder of the old account.
Ciao.
Felix