PHP Fatal error: Call to undefined function mail()
[lakostis@lks ~]$ php-4.4.6 -r 'if (function_exists("mail")) { echo "OK\n"; } else {echo "ERR\n"; }' OK It been eventually broken in 4.4.3 releases and fixed in 4.4.4+ see http://lists.altlinux.org/pipermail/sisyphus/2006-August/085654.html for example.
The same goes for php5: [lakostis@lks ~]$ php-5.2.1 -r 'if (function_exists("mail")) { echo "OK\n"; } else {echo "ERR\n"; }' OK