So, you’re using sendmail to try and send emails from php/wordpress and it’s not working?
Are your mail logs (/var/log/mail.log) showing nrcpts=0 ??
Make sure the sendmail_path in your php.ini file (/etc/php5/apache2/php.ini) is set up correctly.
It should probably be…
1 | sendmail_path = /usr/sbin/sendmail -t -i |