Doesn't works with php 7

Hello,

could it be some lack of configuration between php7 and sendmail ?

Something like :

from php.net

The user that the webserver runs as should be added as a trusted user to the sendmail configuration to prevent a ‘X-Warning’ header from being added to the message when the envelope sender (-f) is set using this method. For sendmail users, this file is /etc/mail/trusted-users.