Ví dụ, nếu một hệ thống khách hàng có tên là gắn kết userbeast / nhà từ một máy chủ có tên homebeast, userbeast không thể tái xuất / nhà. Khách hàng có nhu cầu gắn kết / home phải làm như vậy trực tiếp từ homebeast. | Configuring Mail Services 479 Using the Postfix Mail Server After you read this section you might decide that Sendmail is far too complex and baffling or at least more complicated than Postfix. While Sendmail might surpass Postfix in terms of configurability and features this is only true of corner cases that is of extremely obtuse or unusual mail system configurations. Postfix is used every day at sites that handle thousands and tens of thousands of messages per day so Postfix probably provides all of the functionality you ll need with a fraction of the frustration and aggravation that accompanies learning arcane configuration hieroglyphics. The best part is that Postfix is fully compatible with Sendmail at the command level. For example the command to regenerate the Postfix alias database is newaliases the same name that Sendmail uses the primary Postfix daemon is named sendmail just like Sendmail. The similarity is deliberate for Postfix was designed to be a high-performance easier-to-use replacement for Sendmail. A single example might illustrate why it is easier to configure and use. As you learned in the previous section the unintuitive Sendmail syntax for defining a mail relay host is Postfix s syntax is eminently clearer relayhost If this admittedly simple example doesn t convince you that Postfix is easier to configure and use consider this it is Sendmail not Postfix that needs a meta-configuration-language the m4 macros described earlier to generate or modify configuration files. Switching to Postfix By default Fedora Core and RHEL use Sendmail. Switching to Postfix is simple but before doing so stop Sendmail service sendmail stop You want to stop Sendmail before changing anything so that no incoming mail gets stuck in Sendmail s queues before it is delivered. Of course you should make sure that Postfix is installed rpmquery postfix 480 Chapter 21 Install Postfix before proceeding. Otherwise to make .
