I finally found the solution for the ones stuck with there BCC in the electron cash wallet because of electrum 2FA wallet.
error : rejected mandatary 16.....

in your electron cash wallet. choose new/restore from your menu.
choose restore and choose make 2fa wallet, NOT standard
import old wallet by enter your seed
he will confirm that it is a 2fa wallet and ask if you want to keep or disable, choose DISABLE
now you will see your new wallet, with your BCC, and the trusted 2fa symbol right below corner will say it is disabled.
put the server on  electroncash.casharia...  or electrum.abc....
send your bcc to your exchange bcc address.. and there they go, no rejection anymore