groupadd vmail -g 1001
useradd vmail -u 1001 -g 1001
wget http://internap.dl.sourceforge.net/sourceforge/courier/maildrop-2.0.2.tar.bz2
tar jvxf maildrop-2.0.2.tar.bz2
./configure --enable-sendmail=/usr/sbin/sendmail --enable-trusted-users='root vmail' --enable-syslog=1 --enable-maildirquota --enable-maildrop-uid=1001 --enable-maildrop-uid=1001 --with-trashquota --with-dirsync
make
make install
注意源碼安裝的，將courierauthconfig 命令鏈接到/usr/bin裏，假設裝在：
/usr/local/courier-authlib/bin/courierauthconfig，則：
ln -s /usr/local/courier-authlib/bin/courierauthconfig /usr/bin/courierauthconfig
這樣編譯出來的maildrop才會ourier Authentication Library extension enabled.
maildrop -v
maildrop 2.0.2 Copyright 1998-2005 Double Precision, Inc.
GDBM extensions enabled.
Courier Authentication Library extension enabled.
Maildir quota extension enabled.
This program is distributed under the terms of the GNU General Public
License. See COPYING for additional information.
如果沒有顯示Courier Authentication Library extension enabled.說明你的maidrop還不支持courier auth，請仔細檢查，重新編譯
maildrop建議不要自定義目錄安裝，可以減少不必要的麻煩，刪除很方便：直接在已經編譯的源代碼目錄 make uninstall 就行
配置main.cf和master.cf使postfix調用maildrop
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
vi /etc/postfix/main.cf
virtual_transport = maildrop
maildrop_destination_recipient_limit = 1
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
vi /etc/postfix/master.cf
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/local/bin/maildrop -w 90 -d ${user}@${nexthop} ${recipient} ${user} ${extension}${nexthop}
調試maildrop是否正常工作
從其他郵箱發一份郵件到你新建立的email地址，看到類似log記錄
May 10 07:21:05 mail postfix/pipe[13994]: 78DCC156AE7: to=frank@domain.com, relay=maildrop, delay=0, status=sent
(domain.com)
看到relay=maildrop 並且log沒有報錯，則說明maildrop已經正常工作
FAQ：
1. 編譯安裝的時候出現以下報錯configure: error: pcre.h not found - install PCRE from www.pcre.org
請安裝pcre-devel包