The use of other MTA replace of Sendmail is a troublesome thing, but also users tend to spend a lot of time to get familiar with the allocation and use of new MTA. With Postfix, user can use a lot of owned configuration files (such as access, aliases, virtusertable and so on), simply click in the master.cf definition. In addition, users can use command “sendmail” to start Postfix. However, the use of one software to replace software need to solve specific problems. Part of the reason is because the safety features of Postfix. The most typical problem occurs in root users send mail. Postfix generally do not improve their authority to deliver the mail, which means root users send mail needs to define alias for the root definition of aliases such as “root: someuser”. This will also affect the occurrence of several mailing list modules, especially SmartList.
Sendmail has a prominent problem is scalability and performance. For example, if user requires restart Sendmail to automatically update the configuration file (such as virtual host redirect messages) will occur problem. Because Sendmail generates a new process to deal with sending and receiving messages, and these processes exist until the end of transmission. So that user cannot correctly restart the Sendmail. For Postfix, the user only needs to send the command “postfix reload”, Postfix will reload its configuration files.
Sendmail vs Qmail
First of all, sendmail is MTA with a long history of the development, and current version is 8.10.2. Currently, Sendmail has insurance in portability, stability and guarantee that no bug. But Internet has many posts are about Sendmail, if the attack, this is a nightmare for administrators. Sendmail has a group of experienced Sendmail administrators in the process of development, and Sendmail has a large number of complete documentations. A lot of these documents are important for a variety of Sendmail features to good use and the current Sendmail is a mature MTA.
However, Sendmail has some shortcomings, its characteristic function as a result of the complexity of the configuration file. Although, generating the configuration file by using the M4 macro is easier, it is not an easy thing to master all of the configuration options. Sendmail had a lot of security vulnerabilities in the past versions and the prevalence of Sendmail will become the target of the attack. Another problem is that Sendmail is the default configuration with security features minimal, so Sendmail is often easy to attack.