Notice: This material is excerpted from Special Edition Using Microsoft Exchange Server, ISBN: 0-7897-0687-3. The electronic version of this material has not been through the final proof reading stage that the book goes through before being published in printed form. Some errors may exist here that are corrected before the book is published. This material is provided "as is" without any warranty of any kind.
Today, the latest craze is the Internet. Exchange provides Internet electronic mail through the use of a robust Simple Mail Transfer Protocol (SMTP) connector service. The Internet Mail Connector service is used to allow Exchange clients to send and receive messages to and from people across the Internet. Clients do not need to be directly connected to the Internet to use this functionality.
This connector is one of the core components of the Exchange server; it integrates directly with the rest of the mail services. You can configure the connector as a stand-alone solution or use it as the backbone connectivity protocol.
In this chapter, you learn the following:
Learning the Internet Mail Connector (IMC)
The Internet Mail Connector is a versatile connector that relies on industry standards to allow seamless integration with Exchange and existing SMTP mail systems. The connector provides message transferring with any other system that uses the SMTP protocol.
The Internet mail Connector (IMC) is a Windows NT service that integrates into the Exchange architecture. Users from single or multiple Exchange or MS Mail 3.x sites can communicate with the Internet via the IMC.
Client workstations do not need to have an Internet connection to use the IMC connector.
The functionality provided with the IMC connector complies with Internet standards. The service relies on a set of standards that have been ratified over the past 30 years. These standards are a set of published documents known as Requests for Comment (RFCs). These are the guidebooks for developing applications to be used on the Internet. Following is a list of the key standards to which the Internet Mail connector adheres:
These RFCs allow for seamless integration with other SMTP mail systems across public and private Internet networks.
Exchange supports a variety of connection methods, using IMC as the message connector.
Following are different ways to use IMC in a production environment:
MS Mail users can leverage the gateway in Exchange to provide Internet connectivity.
The IMC integrates directly with the Exchange server.
The IMC connector can be used to link multiple Exchange sites.
The IMC connector can be used to allow MS Mail 3.x to communicate with Exchange sites.
The IMC connector can send and receive message to Windows 95 client workstations.
Setting up the Internet Mail Connector Components
The Internet Mail Connector has many new features that are not available in the MS Mail 3.x SMTP gateway. These new features offer a balance of power and flexibility to route messages over SMTP networks. As described in the preceding section, you can use the IMC's rich feature set in many ways.
After it is configured, the IMC connector transfers messages to remote SMTP mail systems by initiating a connection. When the connection is made, the messages are transferred across systems.
For incoming messages, the IMC connectors listens to a TCP/IP port for connection requests. In similar fashion, once the remote system establishes its connection with IMC, messages and data are transferred into Exchange.
Inside the Exchange site, the IMC connector converts the message to an Exchange-format message and routes it to the Exchange recipient. The user will not notice any difference between an SMTP message and a normal Exchange message.
Setting up Internet Mail Connector Components
Before you configure and run the Internet Mail Connector, you need to meet these requirements:
These are the TCP/IP settings that enable DNS lookups on the Exchange server running the IMC connector.
The DNS entries for server dgbdc1 in the domain dgenesis.com.
Setting up the Internet Mail Connector
After you meet the initial requirements for the IMC connector, you can begin to configure the connector. Following is a list procedures to use as you configure the IMC connector:
You can configure all options from the Exchange Administrator program; select the Internet Mail Connector from the Connections section of the site hierarchy (see fig. 21.8).
Selecting the Internet Mail Connector from the Exchange Administrator program.
The IMC connector is very complicated and has a multitude of options. Prepare yourself by setting aside a few solid hours to set up the IMC connector.
You must select an Exchange mail box that will receive notification regarding the function of the Internet Mail Connector. This mail box can be an admistrators one or special account created for this purpose. Whichever option you choose, just make sure that the mail box is checked periodically to catch important notfication messages sent by the connector.
1. Open the IMC Connector property pages(see fig. 21.9) for the server that you want to configure.
A blank IMC connector tab.
2. Click the Change button to the right of the Administrator's Mailbox box. The dialog box shown in figure 21.10 appears.
Select the administrator message account.
3. The admnistrator message account is used to send notices of events associated with the IMC connector and is similar to the postmaster account on the Sendmail system for UNIX. This account is the default account for message errors, bounced mail, problems with the connector, and other administrative notifications.
4. Define the notices to be sent to the administrator message account.
Define the notices to be sent to the administrator message account.
5. From an administrative standpoint, selecting all the notifications is beneficial. If the volume of the notices is too excessive, change the administrator account to a public folder for the Exchange administrator group's use, or try to troubleshoot the cause for the notices before decreasing the notification settings.
The address space entries for the Internet Mail Connector define which message are routed through it. You must make at least one entry in this page to activate message routing through the IMC. The following steps guide you through creating and editing address space entries.
1. From the IMC Connector property page, select the Address Space tab (see fig. 21.12).
This property page displays Address spaces entries for the IMC .
2. Click the New Internet address space button. The dialog box in figure 21.13 appears.
Create a new Internet address space for the IMC connector.
3. In the Address Space property page, you can enter multiple Internet domain names, MS Mail server names, x.400 names, or other connector names to route messages through this IMC.
4. Click OK to set the configuration.
5. From the IMC Connector property sheet, click Apply to set all the configuration settings. You see a reminder that you have to stop and restart the IMC connector service.
6. Open the control panel—services and locate the Exchange Internet Mail Connector service (see fig. 21.14). If the service is already running, stop the service, then restart it for your new setting to take effect.
NT service for the IMC connector.
7. Select the "Site Addressing" icon in the Administrator programÕs display window and open its property pages.
8. Click the Site Addressing tab. The Services dialog box appears (see fig. 21.15).
Global site-addressing properties.
9. The addresses in the Services dialog box are the global settings for all recipients at this particular site. Make sure that the recipient address for the IMC Connector is the same as what is entered in the MX record of the DNS.
At this point, the IMC connector should be up and running. The IMC connector should be listening to port 25 of the TCP/IP protocol stack on the server—the port specified in RFC 821 for SMTP mail transferring. Now you can proceed to configure the additional options of the IMC connector.
You can modify the settings for inbound and outbound transfer modes, connection limitations, delivery options, and message queues. Follow these steps:
1. From the IMC Connector property pages, select the Connections tab (see fig. 21.16).
Configure the IMC connector connection properties.
The None option is a great tool to use in debugging the IMC connector. When this option is selected, you can keep the IMC connector service running but restrict messages from being transferred from the site. Users will not notice any difference in their work, because messages will just queue up on the server until the transfer mode is reestablished.
2. In the Transfer Mode section, click a radio button to indicate whether messages will be incoming, outgoing, both, or neither.
3. Click the Advanced button to set the following options (see fig. 21.17):
Configure the advanced settings for the Transfer mode.
4. These options can be set based on the resources in your environment.
5. Configure the message delivery settings.
6. The IMC connector allows you to use the DNS to resolve SMTP Mail message routes or use a single SMTP relay host. If you choose the DNS option, the IMC attempts to connect with the various destination SMTP mail systems directly. If you do not want to have Exchange perform the actual message transfer to the remote hosts for performance or security reasons, you can specify a SMTP relay host. Exchange is not a relay host. A relay host has the capability to receive SMTP mail, look at the header destination information, and then perform the message transfer to the remote host. Typically, the smart host functionality is run on a UNIX server. The process is known as sendmail.
7. The DNS option removes the need to have a UNIX server running sendmail just to relay messages to remote hosts.
8. An additional option is to configure the message-delivery options based on domain. Message delivery can be based on Domain Name Service (DNS) lookup. The IMC connector can perform a DNS request before forwarding messages to the appropriate destination. With the MS Mail 3.x SMTP gateway, you were forced to point the gateway to an existing SMTP relay host, which would actually deliver the mail to the final destination. The MS Mail 3.x SMTP gateway forced users to manage two servers to transfer Internet mail (see fig. 21.18).
Configure the advanced settings for the SMTP message delivery.
9. This is useful if it appears the IMC is having a difficult time transferring messages to a particular remote host. You can configure an individual entry for that specific domain causing message transfer problems. Entries can be in the form of domain, sub-domains, and IP addresses. You can use wild cards as well.
10. Define inbound connections.
11. You can configure the IMC to receive messages from all incoming hosts or reject remote hosts based on your input (see fig. 21.19).
Configure the incoming connection to be accepted by the IMC connector.
12. You can specify entries only in the form of IP addresses and sub-net mask of the remote host to be rejected or accepted. This is useful when remote hosts are having a difficult time communicating with the IMC connector or when a particular remote host has a history of transferring junk messages or corrupt data.
Typically, as your users subscribe to Internet listserv mailing groups, a wide variety of mail systems will attempt to communicate and transfer mail into the system. Some of these remote systems do not adhere to the RFCs like the IMC connector. This can cause communication problems between the systems. Suppose that I speak English and am from the West Coast, and that my business partner speaks English and is from the East Coast. Both of us speak English, but we may not always be able to communicate if our accents affect our speaking abilities.
13. Define the Connector message queue retry intervals.
14. This option is used to define the retry attempt interval for the IMC connector, if it encounters a host to which it cannot transfer a mail message. The reason for the retry is that the remote host is too busy to process another communication request or is otherwise unavailable. The IMC connector queues up the message and waits until the retry interval expires before trying to transfer the message to the remote host. The default setting retries the first time in 60 minutes;, the subsequent retries are made at 150% of the set time interval.
15. If you use the default setting—the initial retry at 60 minutes—subsequent retries occur at 1 hour, 1.5 hours, 2.25 hours, 3.4 hours, 5 hours, 7.5 hours, and so on, for a total 8 retries over 72 hours.
16. Select the message time-outs button to configure more specific retry intervals (see fig. 21.20).
Configure the message time-out settings to drop remote connections from the IMC connector.
17. Notice the granularity of the message queue retries. You can configure a specific retry interval based on the priority level of the mail message.
18. Make sure to apply your configuration changes before you move to another configuration tab. Remember that you have to stop and restart the IMC connector service after you complete your configurations.
This section explains how to configure the default message content format, Exchange rich text formatting options, and message formats for individual domains.
To configure the options for inbound and outbound messages, follow these steps:
1. From the IMC Connector property pages, select the Internet Mail tab.
2. The first option to select the message content type for attachments. You have the option of configuring the IMC connector to send and receive message via MIME or uuencode. MIME provides support for a variety of file formats, which do not get broken up or encoded into the mail message as in uuencode. MIME support separates the attachments from the text portion of the message, retaining the original format.
3. Choose the MIME character set translation standard(see fig. 21.21). The default option is to use the ISO 8859-1 standard for MIME outbound mail messages.
Configure the MIME character set translation.
4. Use the pull-down menu to select the Non-MIME character set translation. The default option for uuencode messages is US ASCII for both inbound and outbound messages.
To send message content to the MS Mail 3.x SMTP gateway, make sure that you are using uuencode. The MS Mail 3.x SMTP gateway does not support MIME attachments.
5. Click the E-Mail Domain button. The E-Mail Domain dialog box appears (see fig. 21.22).
Use this dialog box to specify message content by e-mail domain.
6. This dialog box allows you to configure specific character sets, message content formats, and maximum message size for messages transferred through the IMC connector.
7. Click Add to create additional e-mail domain entries, Edit to change
an existing one, or Remove to delete one. When you are done with these
settings, click OK to return to the Internet Mail Connector property pages.
Figure 21.23 shows the dialog shown when you click the Add button.
Dialog box for creating a new e-mail domain configuration with message content options.
8. Click the MIMI Types tab to define MIME attachment formats.
Configure MIME attachment formats.
9. From this property page, you can configure the MIME types (see fig. 21.24). MIME types include support for Microsoft Word documents, video files, audio files, HTML documents, binary executables, and other format types.
10. Click the New button to create an additional MIME type. The New MIME Type dialog box appears.
11. In figure 21.25, for Microsoft Word, enter the MIME content type and the associated extension. The Microsoft Word MIME type is "application/msword" and the associated extension is ".doc". When done, click OK to set the change and activate this new content type.
Create a new MIME type or edit an existing type. You can configure for document formats, multimedia formats, or even application binary formats.
Interoperability defines how display names are sent with outbound messages and how to set the maximum number of characters per line for outbound messages.
To set up the interoperability options for the IMC connector, follow these steps:
1. From the IMC Connector property page, select the Internet Mail tab (see fig. 21.26).
Define the interoperability options for the IMC connector.
2. Click the Interoperability button in the message content section of the Internet Mail tab.
3. The IMC connector sends outbound messages with the display name of the sender/creator and the sender's alias. The display name typically is the senders full name, first and last. If you have a user named Fred Rodriguez, for example, his alias might be fredro and his display name, Fred Rodriguez. Use the interoperability settings to maintain uniformity.
4. You can set the following options to maintain interoperability: Message text word wrap, disable out of office response, disable automatic replies, and disable sending display names to the SMTP hosts.
5. In the example above, you should check the box to make sure to send the display names in the outbound messages.
6. In addition, you choose when to use MS Rich text formatting in messages (see fig. 21.27).
Listed are the options of when to send RTF formatting in outbound messages.
7. The three options allow the user to select when they wish to send RTF data, always send RTF data, or never send RTF data. If this IMC connector only communicates with an MS Mail 3.x SMTP gateway, you should select the option to never send RTF data as the MS Mail SMTP gateway will not be able to understand this information.
8. Set the maximum number of characters per line.
9. Also, if you choose the uuencode type in the Attachment section, the next window will give you the option to define the text word wrap. The default is set to 76 characters.
The MS Mail 3.x SMTP gateway expects to see 76 characters in incoming messages.
10. Define the Message size limit.
11. Open the General tab (see fig. 21.28).
The General tab allows you to set the maximum message size.
12. This option allows you to configure message limitations for the IMC connector.
These settings deal with the actual message settings for the IMC connector.
1. From the IMC Connector property sheet, select the Advanced tab (see fig. 21.29). From this tab menu you can define the message parameters, maximum message transfer times, and the message transfer quotas.
The Advanced tab allows you to configure message transfer parameters.
2. Message parameters are used to limit the number of unread messages, to set the time to back off from message transfer, and to set a maximum unread message time. The values are set in the number of messages, and in number of minutes.
3. The second portion of the advanced tab menu, defines the maximum transfer times broken down by urgent , normal, and non-urgent messages. These values are set in minutes. And can be used to close connections that would otherwise bebe held open for long periods of time. This quota helps to reduce the amount of traffic to single hosts.
4. The last set of values is used to set upper limits for the size of messages transferred from the IMC connector to the remote hosts.
5. Click Apply when done modifying these entries to set your new values..
6. Next select the "Delivery restrictions" tab menu(see fig. 21.30). Use this tab to restrict message delivery to certain users or to restrict those users from sending outbound SMTP mail through this IMC.
Users can be granted access rights to use the IMC connector or restricted access to the IMC connector.
7. You have the option to either grant users access to the ICM connector or on the flip side, deny users access to the ICM connector. On the left panel you can manage the usage by adding users who can connect. On the right panel, you choose who cannot connect. Figure 21.31 show the two windows of the IMC's Delivery Restrictions property page.
You can manage access down to the user level.
8. IN addition to individual mailboxes, you can set delivery restrictions to distribution lists and and custom recipients as well.
After you configure the IMC connector and have the NT service running, you can configure the following additinal feartures to assist you in managing the connector. .
9. From the IMC Connector property pages, select the "Internet Mail" tab.
10. Your first option is to check the "Enable message tracking" field. This will log information about the daily IMC transactions to a common log, that can be browsed to find transmission data on a particular message.
11. Your next option is on the Queues tab(see fig. 21.32). In this tab, you can get real-time statistics on the current processing of IMC connector data.
This tab provides real-time data about the status of messages in the ICM connector queue.
12. If you check the queue and see that several messages are waiting to be processed or transferred to another system, you can begin to diagnose where you may have a problem.
13. Select the Diagnostic Logging tab (see fig. 21.33).
From this tab, you can specify what level of service logging you need for the IMC Connector.
14. Logged information gets written to the common NT event logs. On the left panel, the IMC service(known as MSExchangeIMC in the event log) is listed. The right panel lists the actual log category options. These include:
15. Typical configuration of auditing or logging is to keep each active process set to the minimum log level. In the event that the IMC connector queue begins to back up, you may want to increase the logging level. Turning the logging on to maximum, will flood the event log with many additional messages for you to sort though. Once you have solved the problem, I would suggest returning you logging levels back to the minimum level.
16. Select the Connected Sites tab for the option to view the Exchage sites reached through this IMC." To configure routing to an additional site, click the new button at the bottom of the tab (see fig. 21.34).
This option shows the additional sites connected to the IMC connector.
17. Adding a connected site creates additional routes for messages. Additional Exchange sites, as well as MS Mail 3.x post offices, can be routed to take advantage of the IMC connector.
18. Enter the organization and site of the additional routed post offices when adding a connected site.
Enter a value for the organization and the site.
19. After you enter the site name, click the "routing address" tab to complete the new message route. The Properties dialog box, shown in figure 21.36, appears.
Complete the message route with a message type and post office.
20. Enter a type of mail connection. You can add an SMTP type and include the destination mailbox address.
The IMC connector runs as a single NT service per server. Typically, you have one connector per organization to service the public Internet connection. Additional connections may be needed if you are going to use an SMTP backbone to move messages throughout the organization. The IMC connector is robust and can handle several thousand users. To balance the load, you can set up additional IMC connectors to distribute the processing.
To allow coexistence between two or more IMCs you must perform the following adjustments:
1. In the Address Space tab Modify the entries for existing connectors to accomodate the address space of the new connector.
2. In the Connections tab, modify the maximum inbound and outbound sessions, along with what is specified in any new connectors.
3. Finally, for the new connector to resolve properly in the DNS, you must modify the DNS or host file to reflect a new connector's IP address.
Following are special routing suggestions for sites that have multiple IMCs:
Testing the IMC Connector
When the configuration of the service connector is complete, the last thing to do (after you stop and restart the service) is test the connection. Use the following steps to test your Internet mail connection.
First, send a message from an Exchange client on your site to a remote SMTP server. Verify that the message was properly received.
Examine the body of the message to make sure that any attachments came through without a problem.
From the remote host, send a message back to the IMC connector. Verify that the message was properly routed to the appropriate mailbox. If the message is delayed or does not reach the destination mailbox, you must track it down by using Exchange's troubleshooting tools. Refer to Chapter 24 for more information of such tools. A good place to startto verify the working state of the IMC connector is first the IMC Queues tab and then the Windows NT Event Viewer for any alert messages.
The IMC Connector is a full-featured SMTP Internet Mail Connector. The IMC connector offers numerous configuration selections to give the administrator full control of the service. In addition to being aservice, the IMC connector architecture is scaleable to include MS Mail post offices, Exchange sites, and Internet access clients.. The IMC connector extends Exchange into the Internet.
This chapter explained the connection between Exchange and remote SMTP mail systems. For more information, see the following chapters:
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