Exim4 and PHP and PHP-CGI mail() function using incorrect From: and applying Sender: headers.
If you’re using Exim4 and PHP as a module or as a CGI with suexec. You may have noticed some issues with your mail. Specifically you would have noticed that either the “From:” header was using “nobody@machinename” or “user@machine name, its also possibly that you had an additional header called “Sender:”.
There are two things you need to do to fix this. You first need to make sure that your “php.ini” has the following value “sendmail_path = /usr/sbin/sendmail -t -i”. Which is the default, double check this variable as it might be set to something else.