Comparison of the three popular email systems

For the comparison of the three popular mail systems-Linux Enterprise Application-Linux server application information, see the following for details. Considerations:

In fact, we only use the many configuration options of sendmail. If you want to have a higher understanding of MTA, it is very necessary to study it. QMAIL configuration is relatively simple. The configuration files are all under the control folder and contain the POP3 service.

Security:

Qmail is considerate in terms of security. It will only return to the delivery status after being written to HD. It has also been rewarded with security vulnerabilities, which means it is safer. However, qmail does not verify the domain name of the sender of the email envelope to ensure the correctness of the domain name. Therefore, there are many spam mails. Qmail will receive and Judge emails that are not on the local machine. It is also a drawback. the SENDMAIL software itself has many vulnerabilities (as mentioned in the Security Report) and can use rbl.

Speed:

Qmail can deliver about 20 emails concurrently. The daily processing capacity is 486 of which can be processed by server performance, which is better. sendmail or other messages are different when processing the mail queue, so the speed is far worse than QMAIL (I have not seen it yet)

Bandwidth:

QMAIL is connected once for each mail, while Sendmail only sends one copy of the mail to the target mail server.

To sum up, despite comparing the results of QMAIL "SENDMAIL, but from the more desirable SEMDMAIL and its upgrade POSTFIX, it is said that the source code of QMAIL is relatively easy to understand, you can consider the opportunity to study its source code, go deep into the configuration of SENDMAIL.