I have an Ubuntu machine hosting a site (apache2), running Sendmail. When I "sendmail -f user@mydomain.com user@wherever.com < some-email.txt" from a terminal window on this machine the email comes through no problem (/var/log/mail.log substantiates this). For whatever reason I CANNOT get sendmail working from a php script on my site.
I have tried using backticks, system(), exec(), etc. I have also tried calling an external perl script (which uses a system call) from the php script. I still get nothing. There is no entry whatsoever in /var/log/mail.log. It's as if sendmail is not even being invoked through the scripts. When I run the "external" perl script from a shell manually it works great.
My guess is that this has something to do with running as www-data user from the website but I am a bit of a noob and am so far unable to track down any info on how to address this. If anyone has any ideas I would greatly appreciate it.