邮件应用中可能回又如下的应用需求：
某销售A只能收到来自163.com及sina.com的邮件某技术员B只能给内部用户发邮件，不允许向外网发邮件，但可以收到外网邮件某主管可以收发内、外网邮件......Hello!
I have the same problem:
1. I need to permit some internal users (not all) to send mail to any external user (Internet) 2. I need to permite any external user to send mail to some my internal users (not all)
In fact, the problem is: just "some" of my internal users have permission to receive mail from and send mail to the Internet.
How can I solve this?
View this article only 新闻群组：mailing.postfix.users 日期：2002-12-04 15:18:04 PST
In the example below, the same list of restricted_users is used for controlling both who can send and who can receive internet mail. If you don't require the local_plus feature, just leave that part out.
in main.cf:
use restriction classes to make restricted_users file more readable. smtpd_restriction_classes = local_only, local_plus
local_only = reject_unauth_destination permit_mynetworks reject
local_plus = check_recipient_access hash:/etc/postfix/local_plus check_sender_access hash:/etc/postfix/local_plus reject_unauth_destination permit_mynetworks reject
this is the default setting, required for this setup. smtpd_delay_reject = yes
we'll do this in sender restrictions to avoid open relay problems. smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/restricted_users check_recipient_access hash:/etc/postfix/restricted_users
and in /etc/postfix/restricted_users # /etc/postfix/restricted_users # this file contains a list of users only allowed to send and receive local mail # postmap this file after changes # local users not listed here have no restrictions [email protected] local_only [email protected] local_plus
and in /etc/postfix/local_plus: # /etc/postfix/local_plus # this file contains allowed destinations and senders # for users restricted to local_plus # postmap this file after changes miproveedor.com OK
Remember to "postmap local_plus" and "postmap restricted_users" after making changes to them. Remember to run "postfix reload" after changing main.cf
hzqbbc的限制方法（转自hzqbbc的blog）有几个方法：
1) smtpd_restriction_classes = local_only 设置一个限制类别叫local_only，然后参考access(5)的格式做一个访问控制：
local_only = check_recipient_access hash:/etc/postfix/maps/my_rcpt文件my_rcpt内容：
163.com RELAY21cn.com RELAYhzqbbc.com RELAY然后，设置：
smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/maps/mysender mysender内容：
[email protected] local_only 这样凡是Mail from:
按这个方法，还可以设置更多的类别，例如remote_only以及不限制的帐号等。但这些都只对from:限制。而且不管是否SASL后的。所以有一定缺陷。不过，已经达到目的了。
2)使用snapshot版的policy策略根据某个hash表或配置文件，判断对应的sender和recipient是否匹配，匹配就返回OK或者DUNNO或者RELAY等（可能RELAY已经过时，这个是postfix 1.1.x的）如果不匹配就返回错误代码
按postfix所带的smtpd-policy.pl模式，修改一下就可以使用了。详细参考POLICY_README等。
我自己的例子：
1)定义类send2hrall：smtpd_restriction_classes = send2hrallsend2hrall = check_sender_access mysql:/usr/local/etc/postfix/mysql-send2hrall.cf,reject配置文件 send2hrall.cf内容如下：hosts = localhostuser = mailuserpassword = mailpasswddbname = maildatabasequery = select access from mysql-send2hrall where source = '%s'
2)对发给[email protected]的发件人进行审核：smtpd_sender_restrictions =中添加： check_recipient_access hash:/usr/local/etc/postfix/hrallclass在/usr/local/etc/postfix目录下建立该文件# ee /usr/local/etc/postfix/hrallclass# postmap /usr/local/etc/postfix/hrallclass(会生成hrallclass.db)文件/usr/local/etc/postfix/hrallclass内容如下：[email protected] send2hrall 3)设定数据表mysql-send2hrall记录哪些人可以给[email protected]发送邮件数据库中建立表mysql-send2hrall中使用的表，表结构如下：CREATE TABLE `mysql_send2hrall` ( `id` int(11) unsigned NOT NULL auto_increment, `ctime` int(11) unsigned default NULL, `source` varchar(128) NOT NULL default '', `access` varchar(16) NOT NULL default '', `type` char(1) NOT NULL default 'S', PRIMARY KEY (`id`), KEY `source` (`source`,`type`,`access`,`ctime`)) ENGINE=MyISAM AUTO_INCREMENT=12 DEFAULT CHARSET=gb2312;对应数据格式如下source [email protected] [email protected] OK 过程大概如下： 在smtp发送邮件的时候，通过 check_recipient_access 中获知：[email protected]该邮件接收的时候需要根据类send2hrall核查，而该类中定义了发件人核查的需求，从数据库表中获取此需求的具体结果。譬如上例中，如果发件人是[email protected]，获取的结果就为ok，这样smtp将此人发给[email protected]的邮件进行正常投递；其他如果不在数据库表mysql-send2hrall中的人，将根据下面reject的定义进行回绝。