Well, I've been searching Google for weeks now and can't seem to find the answer.
Actually it's not about a certain CMS system, rather it's a global problem for all systems installed. I've had a simple php contact form which did not send out any emails. Now I've installed OpenCart and in its options I've sent that it uses the "Mail" function to email me when an order has been made. To no avail.
To configure my webserver, I've used this guide to the letter: http://www.howtoforge.com/perfect-se...ot-ispconfig-3
In the website's option in ISPConfig I've added
sendmail_path = /usr/bin/sendmail -t -i
but I don't know what else to do.
Please help me troubleshoot this issue!