Application Analysis of mail server for Small and Medium-sized Enterprises

Source: Internet
Author: User
Tags imap email protocols qmail

I. Mail market status of SMEs

The email system is gradually becoming an essential tool for internal and external information exchange in modern enterprises. According to statistics, 30% of Internet businesses are related to emails. An enterprise has its own email system, which not only enhances its image, but also brings practical benefits to the enterprise. Email has become the most important service in the Internet, far surpassing the second search engine. At the same time, with the rapid popularization of the Internet and the development of enterprise informatization, on the one hand, the popularity of Professional Email system owners from the IT industry's high-end-ISP/ICP to the industry's low-end-SMEs is becoming more and more obvious. On the other hand, enterprises are increasingly relying on the Internet to provide high-quality business services. An enterprise's own mail system has become an inevitable trend in the future, a mail address such as "" in addition to showing the company's external name, brand logo, what cannot be concealed is the efficiency of enterprise operations and the speed of market response.

Compared with large enterprises, most small and medium-sized enterprises have disadvantages such as weak technical strength, reserve, small scale, and ability to withstand system disasters and risks. In addition, due to the competitive environment and cost pressure, the IT status of SMEs is also uneven. Therefore, it is necessary to establish a convenient and easy-to-use mail system to make it easy to manage and operate.

Currently, many enterprises use Lotus Note, Exchange or GroupWise as their internal email servers and SMTP gateways. Some ISPs use sendmail (a well-known email server software on Unix/Linux) or some other Unix/Linux-based email servers, such as Qmail and Postfix, to provide mail services.

Group component systems such as Lotus Notes are very powerful commercial software. However, the collaboration functions of these systems and the license fees per client have dramatically increased their overall costs. In fact, many companies that use these systems only need the mail server features.

In addition, the mail server software such as Sendmail and Qmail on Unix/Linux is also a very good mail system. However, if you want to use these mail server systems to provide good mail services for enterprises and ISPs, you must have professional Unix/Linux system maintenance personnel for system maintenance. This will inevitably increase system maintenance costs.

As a powerful Mail Server launched by Microsoft, exchange is easy to manage and maintain, stable, high-performance, and has a very friendly management interface, it has a large market share in the mail server software of small and medium-sized enterprises.

Ii. Requirements of the mail system for SMEs

SMEs have four basic requirements for their email systems: one is based on their own domain names; the other is low maintenance costs; the third is stability; and the other is strong features, strong features: vendors are expected to provide functions such as anti-virus and anti-spam.

In terms of functions, the mail system of small and medium-sized enterprises should implement the following functions.

1. the WWW browser can be used to process emails online, online email receiving and sending functions, automatic Email Forwarding (Forwarding), and email rejection condition setting (Filter ), it can effectively reject various junk mails. The Auto-Responder function supports POP3 mail address book setting and full-text email retrieval.

2. The enterprise-level email system is characterized by massive capacity, efficiency, security, and reliability. It can meet the needs of enterprise-level users for email exchange and serve as an information exchange platform for enterprise-level e-commerce. It can fully meet the needs of frequent internal communication within the enterprise, and maintain a high mail processing speed when the traffic is very large.

3. supports POP3, IMAP4, SMTP, and other standard EMAIL protocols to exchange data directly with other EMAIL systems. Supports most mail client programs, such as Outlook, Eudora, Foxmail, and Becky, meet different user habits.

4. SSL and digital signature technologies are used to ensure mail security. Provides administrators with a WEB-based configuration interface to make system configuration maintenance easy to learn and use. administrators can directly manage user accounts and permissions on the WEB interface and adjust system parameters.

Iii. exchange email solution for common Small and Medium Enterprises

To establish a complete exchange mail solution, you must consider the following aspects:

1. Domain Controller

The domain controller uses the Active Directory function to manage user accounts, verify user passwords, and provide DNS services. To ensure the security of Active Directory information, we recommend that you use the backup domain controller. If a server fails, the backup domain controller can ensure the security of Active Directory information. In addition, we have established a complete backup plan for the domain controller.

2. Exchange Server

The application server is responsible for the routing and mailbox Management of users' mailboxes. It directly faces the client. As the number of users increases, the server requirements become higher and higher. Generally, when enterprise mail is important, we recommend that you use a cluster with two or more nodes.

According to the enterprise's scale and specific requirements on the mail server, three common deployment solutions for enterprise applications are as follows:

1. solution 1:

The two exchange servers are both domain controllers and backup domain controllers. User Account information is stored on the two servers, and mailbox data is stored on the shared disk array, the two exchange servers are used as the MSC cluster. This solution is recommended when enterprise users are less than 500 and have low investment.


1. Secure and reliable: In this solution, both the domain controller and the exchange Server are backed up separately, so that when any one fails, the other server takes over the service immediately to ensure uninterrupted services.

2. High Cost Performance: A small number of servers are used to implement the mail server function and data backup and recovery, which is highly cost-effective.

3. Suitable for Small Enterprises: because the server undertakes the dual functions of user account management and mail management, it is under great pressure and suitable for enterprises with fewer users.

2. solution 2

The domain controller is independent from the application server. The two exchange servers are used as the MSC dual-host machine to provide the MAIL service. The Domain Controller manages user accounts and DNS resolution. If the customer's budget is sufficient, we recommend that you back up the domain controller. In this way, you can implement Dual Backup between the domain controller and the exchange application server. If not, you can regularly back up the domain controller. In this way, when the domain controller fails, you can recover the user account within the time allowed by the user.


1. The application separation between the domain controller and the Application Server reduces the burden on the server and can take on more users.

2. Secure and reliable: The Mail Service uses the multi-host high-availability solution of MSC, which is easy to operate. The domain controller uses a backup controller to ensure uninterrupted business.

3. solution 3

This solution is suitable for large enterprises with sufficient budget. Multiple exchange Server clusters are used as backend mail services. One front-end server is responsible for receiving requests sent from POP3, IMAP4, and RPC/HTTP clients.


1. Flexible performance Scaling: allows users to use a single and consistent namespace when accessing their mailboxes. With a single namespace, users can still use the same URL or POP or IMAP client configuration even if they add or delete servers or move their mailboxes from one server to another. In addition, creating a single namespace ensures that Outlook Web Access, POP, or IMAP Access remains scalable after the organization is expanded.

2. secure and free from viruses: users can place the front-end server as a single access point on the Internet firewall or after the Internet firewall, and configure the Internet firewall to only allow communication from the Internet to the front-end. Because the front-end server does not store any user information, the server provides an additional security layer for the Organization. In addition, you can configure the front-end server to authenticate the request before the proxy request, which will help the back-end server to resist the "Denial of Service" attack.

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