I quote the manual (http://manual.mantisbt.org/manual.confi ... .email.php)
Is it a way to make it work again ? I used the 0.19.3 version of mantis and i really need this feature !! :($g_to_email : Dropped in 0.19.0. All emails are going to be sent to this email address. This can be an email list or an archive address to be used to archive all notifications. If this functionality is not needed, then it can be set to nothing ('').