Where does pop and IMAP go in Linux?

Pop and IMAP are currently the two most popular email receiving protocols. In Linux, both Protocols are supported. How can I choose to deploy the mail client and server as a Linux system administrator?

Pop and IMAP are currently the two most popular email receiving protocols. In Linux, both Protocols are supported. How can I choose to deploy the mail client and server as a Linux system administrator? Sometimes too many options are available, which also makes the system administrator a headache. Since the pop and IMAP email receiving protocols have different characteristics, it is not easy to make a reasonable choice. I have encountered many similar confusions before. Maybe my experience is helpful to everyone.

1. Consider offline reading requirements.

The pop and IMAP email receiving protocols are only responsible for receiving mails, but not for sending and delivering mails. However, there is a big difference in receiving emails. For example, the POP server downloads users' emails from the mailbox on the server to the computer on the client and deletes these emails from the server. Although some clients can retain these emails during the service period by setting them, these emails are only saved as copies, and the working principle of the POP protocol remains unchanged. Therefore, you can read data offline without connecting to the server. Offline reading is the main advantage of the POP protocol. When downloading an email, the POP protocol uses the pull mail method. Therefore, when using the POP protocol to receive mail, you can download the mail to the client at a fixed interval from the mail server. Note that this interval can be set on the client. The system administrator can set the time interval based on the network conditions. When a user's email is large, downloading to the local device will bring about a large amount of network traffic. Therefore, this time interval is not as short as possible. If the system administrator sets this interval, the enterprise's network performance should be taken into account, especially when the email server is deployed on the Internet.

Unlike the POP protocol, the IMAP Protocol does not provide good support for offline reading. As shown in. I use the IMAP client. When the client is set to offline, the content of the last email cannot be opened. On the client, a message is displayed, indicating that the message has not been downloaded from the server for offline reading. To read this message, you must reconnect to the network, select "offline" from the "file" menu, and then select "online work ". In the future, you can choose to read some messages or folders offline. Select "offline" in the "file" menu and select "Synchronize ". You can adjust the disk space option to avoid downloading too many messages. This problem will not occur if the POP protocol is used. It can be seen that the IMAP protocol is not very good for offline reading.

After logging on to the mailbox server, you can read or modify the email content based on your permissions, or send emails. However, in this process, emails from the server are not downloaded to the client. If the POP protocol is used, the mail will be downloaded to the local client regardless of whether the copy is retained on the mailbox server. This is an important difference between the two Protocols. This difference also leads to the difference in the support of the two protocols for offline reading.

To this end, whether or not the mail receiving Protocol needs to be used depends on whether it needs to be read offline. If employees often need to go home to work, and the mailbox server is set inside the enterprise, it is best to adopt the POP protocol. When an employee returns home, because the mailbox server is in the enterprise LAN, he or she cannot read emails through the client, even emails that have been opened before. Because these emails are still saved on the server and are not downloaded to the local device.

2. Consider the security of offline reading.

Although the POP protocol supports offline reading, it also raises a series of security problems. First, users may read emails on different computers, such as at home and in the office. When the POP protocol is used, emails are downloaded from the server and deleted from the server by default. Some emails may be lost because they are stored on different hosts. The IMAP Protocol generally does not download and delete emails from the server, unless the user deletes the emails directly through the delete button on the mailbox server. Therefore, some important emails will not be accidentally deleted if they are stored on the server. However, some pop clients, such as outlook clients, can be set to retain copies on the mail server. With the help of these clients, the defects of the POP protocol can be solved to a certain extent.

In addition, after downloading an email to your local computer, you do not need to pass the authentication on the email server. Any user using this computer can view the local email. This clearly results in email content leaks. If you use the IMAP protocol, you must connect to the server if you need to read the email. That is to say, the email can be read only after being authenticated by the email server. This improves the security of emails to a certain extent. Therefore, the POP protocol is used to receive mails. Because it downloads the mails to the client computer, its confidentiality is relatively poor, which may cause the leakage of the mail content.

Therefore, when selecting which mail receiving protocol is used, you also need to consider the security. For the sake of mail content security, it is best to use the IMAP protocol as the enterprise's mail receiving protocol. If the cost uses the POP protocol, it is best to take certain confidentiality measures on the client. For example, identity authentication is required when a user opens the mail client. To ensure that only authorized users can use this client to read local emails.

3. The network and server have different burdens.

If you use the IMAP protocol, you need to open the email from the server every time you read the email. This is true even if you have viewed emails you have previously viewed. In addition, it will accumulate a lot of emails on the server, occupying a lot of hard disk space. The use of the POP protocol is different. Because the POP protocol regularly downloads emails from the server to the client. Therefore, when you read the email for the first time and read it for the second time, you do not need to open the email from the server. Open the email directly from the local server to avoid repeated access to the server. It can be seen that the use of the IMAP protocol is heavier for the server than the use of the POP protocol. Therefore, when there are many mail users, the IMAP protocol should be used to improve the configuration of the mail server and optimize the performance to reduce the negative impact.

In addition, this will also affect the network burden of enterprises. Because downloading emails from servers, especially those containing large attachments such as images, will occupy a lot of network bandwidth. If enterprises adopt the POP protocol, they may find that the network speed is very slow when they first go to work every day. This is largely because the POP protocol downloads emails from the server to the client after the server is started in the morning. Since no connection is available for one night, the POP protocol will download emails in a centralized manner after startup in the morning. Downloading emails from the email server to the client at the same time may result in network congestion and degrade network performance. After all emails are downloaded to the client, the network performance will be improved. For this reason, if the POP protocol is used, the traffic may be concentrated at a fixed time, which may adversely affect the network performance of the enterprise. If the IMAP protocol is used, the impact will not be great. Although users need to open emails from the server every time they read emails, the traffic is not concentrated, but scattered. Therefore, it usually has no obvious impact on the network. Therefore, the negative impact of the POP protocol on the network may be greater.

Therefore, when selecting the IMAP protocol or the POP protocol, the system administrator needs to analyze the enterprise's network performance and server configurations before deciding which Protocol to adopt.

4. browser support varies.

Under the same circumstances, the IMAP Protocol provides better support for browsers. For example, you can use a browser to send and receive emails. This is useful in some special cases. If a salesperson is on a regular business trip. It needs to use the client or supplier's computer to send and receive emails. In this case, the email client is not installed on the recipient. Even if there is a client, the user does not know how to configure it due to lack of relevant professional knowledge. In this case, if you can use a browser to read, modify, and send emails, you will undoubtedly need to view emails in remote offices. In this case, the system administrator needs to use the IMAP protocol to deploy the mail application. Because the IMAP protocol is used, you can use a browser to send and receive emails.