编译安装tpop3d（使用mysql验证mail用户）
wget http://www.ex-parrot.com/~chris/tpop3d/tpop3d-1.5.3.tar.gz
tar zxvf tpop3d-1.5.3.tar.gz
cd tpop3d-1.5.3
./configure --enable-mbox-maildir --enable-mbox-bsd --enable-tls --disable-auth-pam \
--enable-auth-mysql --with-mysql-include-dir=/usr/local/mysql/include \
--with-mysql-lib-dir=/usr/local/mysql/lib
(注：--enable-tls打开ssl支持，确认已安装openssl，如果不是安装在默认目录，再加上--with-openssl-root参数指定openssl所安装的目录)
make
make install
这时会出现：
configure: error: vmail-sql authentication enabled, but mysql_init doesn't seem to be available.
错误信息。
vi configure，找到
eval "ac_cv_lib_$ac_lib_var=\"mysqlclient \"" ，更改为：
eval "ac_cv_lib_$ac_lib_var=\"mysqlclient -lz \""
然后：
./configure --enable-mbox-maildir --enable-mbox-bsd --enable-tls --disable-auth-pam \
--enable-auth-mysql --with-mysql-include-dir=/usr/local/mysql/include \
--with-mysql-lib-dir=/usr/local/mysql/lib
make
make install
这样就安装完成带Mysql验证的tpop3d，
修改/usr/local/etc/tpop3d.conf文件(如果没有，执行：cp tpop3d.conf.sample /usr/local/etc/tpop3d.conf)：
#
# MySQL authentication options
#
# auth-mysql-enable: (yes | true)
# Enable MySQL authentication.
auth-mysql-enable: true
# auth-mysql-mail-group: (group-name | gid)
# The group name or gid under which access to the mailspool will take place.
# [default: group of user associated with virtual domain]
auth-mysql-mail-group: vmail
# auth-mysql-hostname: hostname [[hostname] hostname] ..
# Host on which to connect to MySQL. Tried in order until a working host is
# found. [default: localhost]
auth-mysql-hostname: localhost
# auth-mysql-database: database
# MySQL database to use for authentication.
auth-mysql-database: yourdatabase
# auth-mysql-username: username
# MySQL username used to access the database.
auth-mysql-username: yourusername
# auth-mysql-password: password
# Password of MySQL user.
auth-mysql-password: yourpassword
# auth-mysql-pass-query: substitution string
# Query template to use for USER/PASS authentication. Must return mailpath,
# password, userid, mailspool type; uses substitution variables as described
# in the man page.
#auth-mysql-pass-query: SELECT mailpath, password, userid, spooltype FROM ...
auth-mysql-pass-query: SELECT CONCAT('/var/mail/', maildir), \
CONCAT('{crypt}', password), \
'vmail', 'bsd' \
FROM mailbox \
WHERE username = CONCAT('$(local_part)', '@', '$(domain)')
由于没有使用vmail-sql中的数据库schema，则要将auth-mysql-pass-query配置参数修改成符合你本地数据库schema的查询条件。详细情况参见：
http://www.ex-parrot.com/~chris/tpop3d/tpop3d.conf.5.html 的A note on MySQLauthentication部分
