[ZendTo] Why is sendmail -f option disabled?

[tibz]

Hello,

We are currently evaluating zendto and have deployed the CentOS Virtual 
Appliance for ESXi, running zendto 4.11-9

We noticed that the return-path was set to "apache at domain.tld"
After looking at the code, I noticed that the option to set the 
return-path is disabled in NSSDropbox.php:

     return mail(
               $toAddr,
               $subject,
               $content,
               $headers // JKF Commented out for now due to security 
concerns ,
               // JKF Commented out for now due to security concerns
               // '-f "'.$fromAddr.'"'
             );

Can you explain why is it commented? (what are the security concerns you 
are referring to)

Thanks
tibz