Windows Server 2003 building a mail server

Windows Server 2003 building a mail server

Because Windows Server 2003 defaults to not installing the POP3 and SMTP services we need to build our mail servers, we need to install them ourselves. Here's how:

1. Place the Windows Server 2003 System CD in the optical drive or mount the image file to the virtual CD drive. In the Control Panel, tap Add or Remove Programs, and in the Add or Remove Programs dialog box, tap Add/Remove Windows components. Hn

2. In the Windows Components Wizard, you need to do the following:

① Install the POP3 service.

Select e-mail Service, double-click Open, and you'll see that it includes both the POP3 service and the POP3 Service Web management, making sure both items are selected. Such as:

② Install the SMTP service.

Select Application server → Internet Information Services (IIS), and in the Internet Information Services (IIS) dialog box, locate SMTP service to ensure that it is already selected. Such as:

③ Click "Next" to install.

At this point, the services we need to build the mail server are already installed.

Next, we need to configure our own mail server.

First, configure the POP3 service.

1. Click "Start" → "Administrative Tools" → "POP3 services" to open the "POP3 Services" window.

2. Create a new domain. Right-click on the native hostname under POP3 services on the left side of the window and choose new → domain. In the "Add Domain" dialog box that pops up, enter the hostname of the mail server you want to establish, that is, the part after "@" in the email address, such as: wgcunion.com. Click the "OK" button to complete the creation of the domain. Such as:

3. Create a new mailbox. Select the new domain you just created on the left side of the window, such as: Wgcunion.com, right-click, select new → mailbox, and set your own mailbox in the Add Mailbox dialog box that pops up. Such as: The mailbox name is Aaron, the password is Aaron. Click the "OK" button to finish. If you need to create multiple mailboxes under this domain, repeat the operation. The mailbox has been created. Such as:

4. Set User mailbox Space

On a Windows Server 2003 (SP1) system-based mail server, the mailbox name and Windows system user account are one by one corresponding. You can therefore set the mailbox space for the corresponding mailbox user by setting the disk quota for the system user, as described in the following steps:

STEP1 Log on to the Windows Server 2003 (SP1) system as a system administrator (such as Administrator). Open the My Computer window, right-click the NTFS partition where the message root is located (such as D-Disk), and select the Properties command.

Step2 in the "Local Disk (D:) Properties" dialog box that opens, switch to the "Quotas" tab. Select the Enable quota management and deny disk space to users exceeding the quota limit check box, and then select the limit disk space to radio button and enter a limit for the amount of space (such as 100MB) and the warning level (such as 90M), as shown in 7-187, on a schedule.

Figure 7-187 "Quotas" tab

STEP3 Click the Quota Entries button to open the quota entries for local disk (D:) window. Click quotas → New Quota Entry menu command to open the Select User dialog box. Click the advanced → find Now button, select the mailbox user in the search results list, and click OK → OK button, as shown in 7-188.

Figure 7-188 Selecting a mailbox user

STEP4 Open the Add New Quota Entry dialog box, select the Limit disk space to radio button, and set the limit space size and warning level. When you have finished setting up, click the OK button, as shown in 7-189.

Figure 7-189 The Add New Quota Entry dialog box

STEP5 returns the quota entries for local disk (D:) window, which displays detailed information about the quota entries that were created in the window. Close the quota entries for local disk (d:) window and click the OK button in the local disk (d:) Properties dialog box, as shown in 7-190.

Figure 7-190 Quota Entries for local disk (D:) window

Second, configure the SMTP service.

1. Select start → administrative tools → Internet Information Services (IIS) Manager.

2. On the left side of the Internet Information Services (IIS) Manager window, select Default SMTP Virtual server, right-click, and select Properties.

3. In the Properties dialog box, on the General tab, set the IP address to the IP address of this mail server. You can also set the maximum number of connections and log records, and so on, we keep the default. Then click "OK" to complete the configuration. Such as:

Now that we've built a Simple mail server with Windows Server 2003, the following task is to connect using mail client tools such as Outlook.

Here's how to configure client tools such as Outlook, Aaron is only presented in Outlook Express, which comes with Windows Server 2003, and other client tools are configured similarly:

1. Open Outlook Express and add a new account. Such as:

2. In the "email address", fill in the previously set email address, such as: [email protected]. Such as:

3. In the "E-mail Server" setting, "Incoming mail server" and "outgoing mail server" are filled in the mail server's IP address, such as: 192.168.31.9. Such as:

4. Enter the user name and password that you set previously in "Internet Mail Login". For example, Aaron sets the user name and password to "Aaron". In addition, the "Use Secure Password Authentication login" must be selected, or the connection will be error. Such as:

5. Next, click "Done" to send and receive mail with the new mail server.

If your friends and you are in the same LAN, you can use this method to build a Simple mail server, the above can only be sent in the LAN to receive mail, how to let the local area network users send mail to the outside?

Configuring POP3 and SMTP

9) The above can only be sent in the LAN to receive mail, how to let the local area network users send mail to the extranet?

To re-server IIS console operations:

Click on "Properties"

Click "Relay", that is, the internal network of mail relay out of the external network. The relay feature is not enabled by default. Trunking as Set

Note: Click on the Radio box "only the following list except (X): When the list is empty, the description can relay any external mail, remember that usually we can not really do this, otherwise less than a few hours, the mail server crashes, we fit to add external network."

If you select the "Allow all computers with authentication to relay and ignore the previous table" option, the server's relay service can be used by all authenticated computer accounts, regardless of the list of restrictions above. However, if the computer account is not authenticated, it is still executed in the limit list above.

10) We now want to send e-mail to the external network: to prove that external Mail has been sent successfully, LAN users can use this mail server to send each other email. If the mail server is bound to a public IP address in the Internet, you can also provide e-mail services to internet users.

11) Below we limit the messages sent:

Description: You can

1) Number of user-connected mail servers

2) Connection Timeout time

3) Whether logging is enabled

12) Authentication: If the "Anonymous access" option is selected, all clients are allowed to send messages out of the SMTP server without a user name and password. You can disable other authentication on the virtual server by selecting this option and clearing the remaining two options. However, it is usually not configured for security reasons.

If you select the Basic Authentication complex option, you can enable basic (clear text) password authentication. For basic authentication, the account name and password are transmitted in clear text. In addition, you need to specify a domain in the Default Domain text box to be appended to the account name for authentication, such as domain grfw.local and user name Winda, then the full user domain name is [email protected]. If you select the Require TLS encryption complex option, you are required to encrypt incoming messages by using Transport Layer Security (TLS) technology.

If you select the Integrated Windows Authentication complex option, the standard security mechanisms provided by the Microsoft. NET Server family are enabled. This security mechanism makes it possible for enterprises to provide secure login services to users. Virtual servers that already use Integrated Windows authentication on the internal system can benefit by using a single, public security mechanism. The Integrated Windows authentication method uses encryption technology to authenticate users and does not require users to transmit real passwords over the network. Note, however, that choosing to use Integrated Windows authentication means that the mail client must support this authentication method. Microsoft Outlook Express Client supports the "Integrated Windows Authentication" approach

13) To prevent a client from connecting to an SMTP server, we block the client IP address as: 192.168.7.26 connection to the SMTP server, when the client sends a message, the SMTP server needs to be connected, and the server blocks it, and the client fails when it sends the message. Of course you can also block a group of computers or prevent the sending of a mail from a domain name. If all is not configured, the default is to allow everyone to connect to the SMTP virtual server, usually without configuration.

14) Description: Mainly prevent SMTP server from being abused by SMTP

(1) Limit message size: 2048, out of this size, the message failed to send.

(2) Limit session size: Sets the maximum amount of data (in kilobytes) that is accepted during the entire connection process, which is the sum of all messages sent during the connection (message body only). You must be particularly cautious when setting this maximum value because the connection message transfer agent (MTA) may submit messages repeatedly, with a default size of 10240KB. This value should be greater than or equal to the value of Limit message size to (KB). To make no restrictions, clear the selection for this check box.

(3) Limit the number of messages per connection: You can limit the number of messages sent in a single connection, and the default value is 20. With this approach, you can improve system performance by sending messages to remote domains over multiple connections. After the set limit is reached, a new connection is automatically opened and the message continues to be transmitted until all messages have been delivered. To disable this feature without setting this limit, clear the selection for this check box.

(4) Limit the number of recipients per message to: Limit the maximum number of people per message received.

(5) Badmail directory: Sets a directory location where a copy of this message is sent to the sender when the retry limit is reached, and the NDR cannot be sent to the senders, which is the Badmail directory. Messages in the Badmail directory cannot be passed or returned. Please check this directory regularly and process these messages, because a full directory can negatively affect SMTP service performance.

(6) Use the LDAP Routing tab to specify the identity and properties of the directory server used for the SMTP virtual server, which stores information about the mail client and its mailbox. The SMTP virtual server communicates with the directory service using Lightweight Directory Access Protocol (LDAP).

(7) in the "Send a copy of an undeliverable report to" text box, you can set a copy of the NDR to be sent to a specific SMTP mailbox when a message is undeliverable. Undeliverable messages are returned to the sender with an undeliverable report (NDR).

(7) Using the Security tab to add Windows user accounts and groups to the SMTP virtual Server Operators list, the operator has permission to access and configure the SMTP server. The system defaults to members of the System Administrators group (Administrators), the "Local Service" that was created after Terminal Services was installed, and the Network Service (Web services) 3 groups. If you do not have a terminal server, you can delete the two groups "Local service" and "Network service". Of course, you can also add other users and group members to the list, making them an operator of the SMTP server.

15) Mail Send delivery settings:

16) Outbound Connection settings:

17) Click "Advanced", note: The mail server sends the received mail to a smart relay host, all outgoing messages are forwarded by the relay host.

18 which users are granted what permissions to the SMTP server

19) Configure the POP3 server:

(1) There are 4 log level selections in the Log Level drop-down list box, if the None option is selected, the POP3 service event is not logged, and if the minimum option is selected, the POP3 service critical event is logged (this example selects this option) and the POP3 service critical and warning event is logged if the medium option is selected; If you select the maximum option, the POP3 service critical, warning, and informational events are logged.

(2) in the root Mail directory text box, you can configure the directory that the mail server uses to store client mail, where you enter the path to the message store. The system default path is \inetpub\mailroot\mailbox under the system area, it is best not to change it, which makes it easier to manage all application servers. Note, however, that this path has a maximum value of 260 characters. Also, the message store must be a directory of a local file system, or a universal naming convention (UNC) path, that is, a network share path, which does not support disk mapping.

(3) If you select the Require Secure Password Authentication (SPA) For all client connections check box, all e-mail clients that are connected to the POP3 server are required to authenticate securely.

(4) If you select the always create associated users for new mailboxes check box, the user that corresponds to the mailbox name in Active Directory or the local computer is automatically created when a new mailbox is created in the POP3 server. This check box is selected by default, otherwise there is no point in creating a user's mailbox because this is an integrated authentication method with Active Directory.

20) Limit the capacity of users to store messages on the server: Because the mail is stored under the C drive by default.

POP3 mail system If you are using Active Directory integrated authentication or local Windows account authentication, the quota file is created by default when you create a mailbox.

The procedure for creating a quota file is simple, just go to the command prompt, enter winpop createquotafile [email protected] [/user:username] command, where "Winpop createquotafile" The command is used to create a quota file; the [email protected] parameter is used to specify the user who created the quota file; The/user:username parameter is used to associate the quota file creation quota file for an existing user account.

Ps: Relay Detailed

4.4 Mail Relay Configuration

If you want to send messages to the extranet, not on the local domain system (such as sending Internet mail), you need to configure the mail relay feature for SMTP. This involves not only the use of mail relay functions, but also aspects such as outbound authentication, the limit of passing connections, and the delivery of target domains. The following are presented separately.

4.4.1 SMTP Relay Feature usage restrictions

In a corporate network, it is not usually permissible for all users to send messages outward, and in the POP3 messaging system, the relay throttling feature can be implemented as follows.

(1) Click the Relay button in the Relay Restrictions option group in the dialog box shown in Figure 4-19 to eject the dialog box shown in 4-32. Here, you set up a client computer account that can use the SMTP virtual server as the SMTP relay server to restrict clients from sending messages outward.

(2) If fewer users are allowed to use the SMTP relay feature, select the "List only" radio button, and then click the "Add" button to pop up the dialog box shown in 4-33. Here are several ways to configure, if you want to add a single computer account, select the Single Computer radio button, and then enter the IP address of the computer in the IP Address text box below. Repeat the above and add one at a time until all the computer accounts that are allowed to use the SMTP relay feature are added. If you want to allow all computer accounts in a subnet to use the SMTP relay feature, select the Computer Group radio button, and then enter the network address of the appropriate subnet in the Subnet Address text box below, and enter the subnet mask for the corresponding subnet in the Subnet mask text box. If you want to allow all computer accounts in a domain to use the SMTP relay feature, select the Domain radio button, and then enter the name of the appropriate domain in the Name text box below.

Figure 4-32 "Relay Restrictions" dialog box 4-33 "Computer" dialog

If fewer users are allowed to use the SMTP relay feature, select the "except for the list only" radio button in the dialog box shown in Figure 4-32, and then click the Add button, which also pops up the dialog box shown in 4-33. The configuration method is the same as described above when you select the "List only" radio button above, and you will not repeat it here. Except that the computer account you added here is not allowed to use the SMTP relay feature.

(3) Click the OK button to return to the dialog box shown in 4-32. If you also select the Allow all computers that are authenticated to relay and ignore the table above check box, the server's relay service can be used by any computer account that is authenticated, regardless of the list of restrictions above. However, if the computer account is not authenticated, it is still executed in the limit list above.

4.4.2 Message Outbound Delivery configuration

When you send messages out of the SMTP relay feature, you also need to make the necessary settings for the SMTP virtual server.

1. Outbound Connection Basic Property settings

The settings for the outbound connection basic properties are configured in the Delivery tab of the SMTP Virtual Server Properties dialog box shown in Figure 4-34.

The options in the Outbound option group are used to set the connection properties of the SMTP virtual server when sending outgoing messages, including retrying the connection interval, allowing the message to be passed on the network (over this time), and when the message is sent out (exceeding this deadline no longer attempting to send). The two options in the local option group are used to set the time for local delay notification and the expiration time-out, except that this is set for message delivery on the local network.

2. Outbound Connection authentication Settings

In addition to the basic property settings above, you can also configure other properties of the SMTP virtual server outbound connection, such as the destination domain for authentication, outbound connections, and outbound connections required by the receiving mail server.

In the dialog shown in Figure 4-34, click the "Outbound Security" button, pop up the dialog box shown in 4-35, the outbound authentication settings are here.

Figure 4-34 "Default SMTP Virtual Server Properties" dialog box 4-35 "Outbound Security" dialog

There are also 3 types of available authentication: Anonymous, Basic (clear text), and Integrated Windows authentication. However, the authentication configuration here is different from the authentication method configured in Figure 4-20, and figure 4-20 configures the authentication method that is required for the mail client to access the SMTP virtual server to send mail, where authentication is performed on the local POP3 messaging system. Outbound pass-through authentication is configured with the authentication method that the SMTP virtual server needs to access the recipient's mail server. Anonymous mode does not require authentication, select clear text mode, you need to specify the user to connect to the server's account name and password, in clear-text transfer, select Integrated Windows authentication method, you also require a Windows account name and password, To authenticate on the recipient's incoming mail server. Table 4-4 Describes a few configuration examples.

Table 4-4 SMTP Virtual server Authentication Mode selection Example

SMTP Transport

Authentication Options

Mail is usually sent to multiple addresses

Disables authentication for the SMTP virtual server. If the message delivery operation to an address fails due to authentication requirements, add a remote domain to the address. Then, enable the authentication of the domain at the same level as the server requires

Mail is usually sent to an address (authentication required)

Determine the level of authentication required for the connection. Then, use the same level to enable authentication for the SMTP virtual server. If you then want to send the message to a different address, establish a remote domain and set various authentication options. If you use this option, the account name used may be the account name used to identify the computer that is set as the relay host

If you select the Anonymous Access radio button, the SMTP virtual server does not need to authenticate when it sends outgoing messages, and of course this requires the recipient's incoming mail server to support anonymous access.

If you select the Basic Authentication radio button, the account name and password of the server you are connecting to is transferred in clear text. This option requires that you configure the user name and password in the user name and password text boxes below, or you can select users in the dialog box that pops up by clicking the browse button. This setting should match the incoming (POP3) authentication requirements of the receiving server.

If you selected the Integrated Windows Authentication radio button (This example selects this option), this option requires a Windows user account name and password. This authentication method also needs to be configured with the user name and password for authentication, as well as by clicking the Browse button to select the user in the popup dialog box, which should also match the incoming authentication requirements of the receiving server. If you want to use the relay service for an SMTP virtual server, you must select the authentication method for Integrated Windows authentication.

If you select the TLS encryption check box when you select the above authentication method, all outgoing messages are required to be encrypted using Transport Layer Security (TLS).

After selecting and configuring the authentication method, click the OK button to complete the outbound authentication settings.

As can be seen from the above authentication mode configuration, this POP3 mail system is usually only applicable to internal network, because the public service of the Internet mail server rarely use this simple POP3 mail system, or may not support the above 3 authentication methods. It is also rare that the authentication here is applicable to all accounts in the POP3 mail domain.

3. Outbound Connection Configuration

In the "Delivery" tab of the dialog box shown in Figure 4-34, click the "Outbound Connection" button, and the 4-36 dialog box appears, where the outbound connection configuration is done.

For outbound connections, in the Limit connections to text box, define the total number of outbound connections that can be connected to the remote domain at the same time. This check box is selected by default and the default limit is 1 000. The minimum number of connections is 1. For incoming and outgoing connections, this check box must be selected for the restriction to take effect.

Specify a time in the timeout (minutes) text box, and if a connection is always inactive for that time period, the Microsoft SMTP Service closes the connection. For incoming and outgoing connections, the default time is 10 minutes.

In the limit the number of connections per domain text box, limit the number of outgoing connections that can be connected to a single remote domain, with a default value of 100. This value should be less than or equal to the value of the limit connections to setting.

Specify the TCP port to use for outgoing transmissions in the TCP port text box. The default port is SMTP Standard TCP port 25, do not change.

4. Outbound connection target domain settings

In the "Delivery" tab of the dialog shown in Figure 4-34, click the "Advanced" button, the dialog box shown in 4-37, the outbound connection target domain setting is here. When you deliver a message, the message may go through more than one server before it reaches the final destination, and in the Maximum Hops text box, you can specify the number of servers that the message is allowed to pass through, often called hop count. After you set the hop count, the SMTP virtual server counts the number of hops in the received row of the message header. When the value of the Received field exceeds the maximum hop count setting, the message is returned to the sender with a non-delivery report (NDR). The default hop value is 15. In the Virtual domain text box, set the destination virtual domain name of the outbound connection to replace the local domain name in the "message from" line in the agreement, not configurable. In the fully canonical domain Name text box, set the fully qualified domain name of the SMTP virtual server. Usually the system is shown by default without additional configuration.

You can use two records to identify and verify computers in a TCP/IP network. The Mail exchange program (MX) record identifies the host and the domain name associated with the computer, the domain name uses the fully canonical domain name (FQDN), and the address (A) record identifies the computer's IP address. When both records are used, the name resolution is faster.

You must specify an FQDN for the Microsoft SMTP Service for which you want to process MX records. The FQDN is used by DNS to identify the host server for the domain, and the syntax is Host.domain. For example: Companya.com may have several host servers, one of which is named Server01, and the FQDN of this server is Server01.CompanyA.com.

To specify the FQDN, you can double-click the System icon in Control Panel, switch to the Computer Name tab in the Pop-up dialog box, 4-38, where you can specify a name, or specify a unique FQDN for the SMTP virtual server you are configuring. When started, the name specified on the Computer Name tab of the System Properties dialog box is automatically used for the FQDN. If you change the name manually or by joining a domain, the new name is automatically used for the FQDN the next time you start the computer, without having to do anything to update the FQDN of the SMTP virtual server.

Figure 4-37 "Advanced Delivery" dialog box 4-38 "Computer name" tab

To override the computer and domain name on the automatically used Computer Name tab, change the FQDN on the Advanced Delivery tab here, but be sure to check that the name you set is valid by clicking the Check DNS name button. The Microsoft SMTP service then uses the specified name instead of the name specified on the Computer Name tab.

In the dialog box shown in Figure 4-37, the Relay host text box can be used to set up a relay host for mail delivery, so that all outgoing messages can be routed to the remote domain through a relay host instead of being sent directly. This type of mail routing is more straightforward and less expensive than other routes. A relay host is similar to a routing domain option for a remote domain, except that after you specify a relay host, all outgoing messages are routed to this server, and when you use a routing domain, only messages from the remote domain are routed to a specific server.

Even if you set up a relay host, you can still specify a different route for the remote domain. The routing domain setting overrides the relay host settings. Enter the FQDN or IP address here to identify the relay host. If you use an IP address, surround it with "" to improve system performance. Microsoft SMTP Service first checks the name and then checks the IP address. The parentheses identify the value as an IP address, bypassing the DNS search.

When a relay host is configured, the "attempt to send directly before sending to a relay host" check box does not take effect. When this check box is selected, the Microsoft SMTP service attempts to send remote messages directly before they are forwarded to the relay host server. The default setting is to send all remote messages to the relay host instead of sending them directly.

If you select the Perform reverse DNS search for incoming messages check box, the Microsoft SMTP Service will attempt to verify that the client IP address matches the host/domain submitted by the client in the Ehlo/helo command. If the reverse DNS search succeeds, the "received" header is intact, and if the authentication fails, the IP address in the received header of the message will appear "not verified", or "RDNs failed" in the received header of the message if the DNS search fails.

However, it is important to note that because this feature verifies the address of all incoming messages, using it affects the performance of Microsoft SMTP Service.

Relevant knowledge points:

First, the key points of knowledge:

1. Smtp,simple Mail Transfer Protocol, Simple Mail Transfer Protocol.

SMTP is typically used to transfer e-mail from a client to a server and from one server to another. The default TCP port is 25. An e-mail server configured with the SMTP protocol is called an SMTP server.

2. Pop3,post Office Protocol, Post Office Protocol, currently 3rd edition

Provides information storage capabilities, which are responsible for saving incoming e-mails to users and retrieving them from the mail server. TCP port 110 is used by default.

3. Imap4,internet Message Access Protocol, the Internet Messaging protocol, is now the 4th edition, when using IMAP, users can selectively download e-mails or even just download some of them.

4. MIME, multi-purpose Internet Mail extension

MIME enhances the ability of e-mail messages defined in RFC 822 to allow the transmission of binary data.

Sound, image, Chinese, etc. use 8 of binary-encoded e-mail messages

5. The process of mail transfer:

1) When the user wants to send an e-mail message, the user interface is used to generate the mail and then send the message to the SMTP server using the SMTP protocol.

2) The SMTP server uses the SMTP protocol to forward mail to the recipient's POP3 server, based on the address of the mail recipient.

3) The recipient uses the POP3 protocol to receive mail from his or her mail server.

6. To install the POP3 and SMTP services:

1) Install POP3 Service: Panel---Add remove program---Add remove component---email service

2) Install the SMTP service: Panel---Add Remove Programs---Add Remove components---Application Server---Internet Information Services (IIS)---SMTP service

7. POP3 Server Authentication: The POP3 service provides three different authentication methods to authenticate users connected to the mail server, that is, local Windows account authentication, Active Directory integrated authentication, and encrypted password file authentication.

1) Local Windows account authentication: Local Windows account authentication integrates POP3 account authentication and Windows account authentication for the local computer. Users can log in to POP3 using their Windows account and password.

2) Active Directory Integrated Authentication

It uses user account information within the Active Directory database to authenticate the user. This method is appropriate for situations where the POP3 server is mounted on a member server or domain controller.

3) encrypted password file authentication

Encrypted password file authentication creates an encrypted file with the user's password, which is stored in the directory of the user's mailbox on the server. During the authentication process, the user-supplied password is encrypted and then compared to the encrypted file stored on the server. If the encrypted password matches the encrypted password stored on the server, the user is authenticated.

8. POP3 creates a directory for each user who has a mailbox in the domain, for example, the directory where the test user message is stored is "p3_test.mbx", and the following path is the absolute path for storing the user test message: "F:\inetpub\mailroot\mailbox\ Szpt.net\p3_test.mbx\p3_20050110090047026500000003.eml ". The e-mail messages that the user receives are stored in the user's directory as a single file until the user retrieves the message with the POP3 e-mail client.

9. Configure disk quotas for the POP3 service

You can use disk quotas to control and limit the disk space used by personal mailboxes on your mail server. This ensures that a single mailbox (and usually the message store) does not consume excessive or unpredictable disk space.

10. Access control (authentication) for the SMTP server

(1) Anonymous access

Anonymous access allows any user to use the SMTP server without asking for a user name and password.

(2) Basic authentication

The Basic authentication method requires a user name and password to be able to use the SMTP server, and the password is sent in plaintext (unencrypted text) on the network with low security.

(3) Integrated Windows authentication

Integrated Windows authentication is a secure form of authentication because the user name and password are hashed before they are sent over the network.

11. Connection control:

You can restrict access to the SMTP server by the IP address of the client computer. By default, all IP addresses have access to the SMTP virtual server. You can allow or deny access to IP addresses in a specific list. You can specify an IP address individually, or you can specify an IP address by group by using a subnet mask.

12. Relay Restrictions

By default, the SMTP service prevents the computer from relaying unwanted messages through the virtual server, which means that if the received message is not sent to the domain it is responsible for, it is refused forwarding.

13. When the SMTP virtual server sends remote mail (that is, the recipient's mailbox is on another service), it looks through the DNS server for the SMTP server (MX resource record) of the remote message, and then sends the message to the SMTP server. However, your SMTP server can also send messages directly to a special SMTP server without having to go through a DNS server, and the SMTP server is responsible for sending messages, a specific SMTP server called a "relay host."

Windows Server 2003 building a mail server