[BlueOnyx:11345] php mailer script

[Wisja.net]

Hi List,

I've been looking into the following problem for the past weeks and can't find a 
working solution. Before I go crazy i'd like to see if someone with php knoledge has 
some pointers or the solution for me.

It is for a 5108R box with php 5.3.12-1 from solarspeed installed.

When looking at the apache error log it gives the following line:
[Tue Sep 18 15:13:04 2012] [error] [client xxx.xxx.xxx.xxx] malformed header from 
script. Bad header=/home/.sites/120/site53/.users: mailer.php, referer: 
http://www.websitename.com/contact/contact.php
The script itself gives a 500 Internal Server Error. The mail is sent to a 
death.letter file in the .user dir of that website.

Is there a specific type of header to use? I think that is has got something to do 
with sendmail not getting the right user 'from' header. But thats just a guess after 
looking at different googled pages. Is someone willing to share a script with me?

I'm looking forward to some nice pointers ;)

Wisja