test Script:
<?php
        $test_var = mail( "aksuska@webflyer.com", "Hi 
does this work?", "It is if you see this!" );
        print "The result is: $test_var";   
?>
No mail is sent, no error reported ($test_var is empty), 
nothing in syslogs. I also tried:
<?php
$fp = popen('/usr/sbin/sendmail -t', 'w'); 
if($fp) {
fputs($fp, "To: aksuska@webflyer.com\n"); 
fputs($fp, "Subject: test\n\n"); 
fputs($fp, "Test of PHP manual mailer"); 
fputs($fp, "\n"); 
pclose($fp); 
print "The result is: $test_var";
}
else {
print "Can't open sendmail!";
}
?>
Which does not print the error message "can't open" 
nor sends an email (nothing in syslogs). Sendmail is 
indeed working, and works without error in Perl:
open MAIL, "| /usr/lib/sendmail -t" # etc.

BTW, I have the exact same problem on my LinuxPPC 
(basically RH) machine.

Please help. Had no problem with earlier versions (last 
was 4.01pl2, I believe), just started when installed 
403pl1.

Location of sendmail: /usr/lib/sendmail
sendmail_path (php.ini): /usr/lib/

Configure:
--with-apxs=/site/apache/bin/apxs 
--with-config-file-path=/site/etc --enable-magic-quotes 
--with-dbase --with-gdbm=/usr/local 
--with-mysql=/usr/local --with-gd=/usr/local 
--with-jpeg-dir=/usr/local --with-ttf=/usr/local 
--enable-calendar --enable-memory-limit 
--enable-trans-sid --enable-bcmath --with-mcrypt 
--with-mhash --with-zlib --with-ftp --enable-wddx 
--enable-ftp