I upgrade my apache from 1.3 to 2.0.36 and php from 4.0.4pl1 to 4.2. Then I found that the mail() can't work and it's can work fine before I upgrade. The configure command of php4.2 is:
'./configure' '--prefix=/usr/local/php4.2' '--exec-prefix=/usr/local' '--bindir=/usr/local/bin' '--sbindir=/usr/local/sbin' '--libexecdir=/usr/local/libexec' '--datadir=/usr/local/share' '--sysconfdir=/usr/local/etc' '--sharedstatedir=/usr/local/com' '--localstatedir=/usr/local/var' '--libdir=/usr/local/lib' '--includedir=/usr/local/include' '--oldincludedir=/usr/include' '--infodir=/usr/local/info' '--mandir=/usr/local/man' '--enable-ftp' '--enable-gd-native-ttf' '--enable-mbstring' '--enable-mbstr-enc-trans' '--enable-overload' '--enable-sockets' '--enable-aggregate' '--with-mod_charset' '--with-mysql' '--with-apxs2=/usr/local/apache2/bin/apxs' '--with-config-file-path=/etc' '--with-imap=/usr/lib' '--with-imap-ssl=/usr/lib' '--with-kerberos=/usr/kerberos' '--with-pear=/usr/local/php4.2/lib/php' '--with-exec-dir=/usr/local/bin' '--with-bz2=/usr/bin' '--with-java=/opt/jdk1.3.1' '--with-oci8=/u02/app/oracle/product/ora816' '--with-oracle=/u02/app/oracle/product/ora816' 

How to resolve it? I wish somebody can help me!