Got the answer myself... Just for your information.. You can add a header containing the messageit
Message-Id: messageid.somemoreid@sendermachinname
You can search for that string in de /var/log/maillog
The same line includes the messageid.
With this ID, you can find more information about the sent mail.. Was is received, or rejected or whatever... With other words, you can now track what happend with a mail message sent from PHP.. Or has someone another solution for this?? (maybe there's a way quiker method to get this info) anybody??