I'm now in 2.6.12
Here is the result of your test command line
[admin@MyHost scripts]$ cat test_msg.txt | /opt/php-4.3/bin/php -d register_argc_argv=1 maillist.php 1
Warning: fopen(/usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/messages/msg_1): failed to open stream: Permission denied in /usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/include/theme/default/imsg_edt.inc on line 512
Warning: fseek(): supplied argument is not a valid stream resource in /usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/include/theme/default/imsg_edt.inc on line 513
Warning: ftell(): supplied argument is not a valid stream resource in /usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/include/theme/default/imsg_edt.inc on line 514
Warning: fstat(): supplied argument is not a valid stream resource in /usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/include/core.inc on line 138
Warning: fwrite(): supplied argument is not a valid stream resource in /usr/local/home/httpd/vhtdocs/MyHost.co.uk/fudforum/include/theme/default/imsg_edt.inc on line 524
FATAL ERROR: system has ran out of disk space<br>
[admin@MyHost scripts]$
I have chmod 755 -R /include and that made no differnce.