qmail にて検証。
postfix, sendmail については不明。。
server.php
<?php var_dump($_SERVER); ?>
.qmail-server
|/usr/local/bin/php /home/apache/htdocs/server.php > /tmp/server.txt
出力
% less /tmp/server.txt array(28) { ["HOST2"]=> string(10) "example.com" ["HOST3"]=> string(7) "example" ["SENDER"]=> string(28) "hoge@example.com" ["RECIPIENT"]=> string(25) "server@example.com" ["HOST4"]=> string(3) "" ["DTLINE"]=> string(40) "Delivered-To: server@example.com " ["HOST"]=> string(18) "example.com" ["EXT"]=> string(6) "server" ["USER"]=> string(5) "alias" ["LOCAL"]=> string(6) "server" ["PATH"]=> string(233) "/var/qmail/bin:/usr/local/sbin:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/kerberos/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11R6/bin:/sbin:/usr/sbin:/var/qmail/bin:/sbin:/usr/sbin:/var/qmail/bin" ["RPLINE"]=> string(44) "Return-Path: <hoge@example.com> " ["NEWSENDER"]=> string(28) "hoge@example.com" ["PWD"]=> string(16) "/var/qmail/alias" ["HOME"]=> string(16) "/var/qmail/alias" ["SHLVL"]=> string(1) "1" ["EXT3"]=> string(0) "" ["EXT2"]=> string(0) "" ["EXT4"]=> string(0) "" ["UFLINE"]=> string(59) "From hoge@example.com Tue Aug 21 02:32:42 2007 " ["_"]=> string(18) "/usr/local/bin/php" ["PHP_SELF"]=> string(34) "/home/apache/htdocs/server.php" ["SCRIPT_NAME"]=> string(34) "/home/apache/htdocs/server.php" ["SCRIPT_FILENAME"]=> string(34) "/home/apache/htdocs/server.php" ["PATH_TRANSLATED"]=> string(34) "/home/apache/htdocs/server.php" ["DOCUMENT_ROOT"]=> string(0) "" ["argv"]=> array(1) { [0]=> string(34) "/home/apache/htdocs/server.php" } ["argc"]=> int(1) }