NetMail Technical White Paper

The intense need to communicate and collaborate throughout the organization and beyond has made e-mail a business-critical application. E-mail makes up the majority of Internet usage today. An estimated 15 billion e-mail messages were generated in the year 2000. According to the Aberdeen Group, an independent market research firm, external e-mail between companies is increasing at a rate of 100 to 150 percent a year.

Many organizations have already reaped substantial rewards by providing their executives, managers, professional and specialty personnel, and administrative support staff with e-mail, calendaring and other collaboration tools. Now they are looking at ways to extend these tools to the deskless workforce. This could literally double the number of users that the information technology (IT) staff must support because deskless workers represent more than 50 percent of employees in the typical enterprise.1

Traditionally, implementing communication and collaboration tools has been a major undertaking, particularly in environments with a large user community. Supporting tens or perhaps even hundreds of thousands of users has meant acquiring, deploying and maintaining a number of high-end servers. User management in this environment has been complex, cumbersome and time consuming. Many organizations have multiple platforms-Linux*, Microsoft* Windows NT*/2000, NetWare® and Solaris*. Many organizations have more than one e-mail and calendaring system, further complicating the environment and placing an additional burden on the IT staff. These factors have made it a difficult challenge to deliver reliable service and acceptable performance to the user community-especially in light of shrinking IT budgets and limited resources.

Novell® NetMail™ provides a solution for organizations facing these and other challenges associated with deploying e-mail and calendaring tools to a large user base. Novell NetMail is a scalable, high-performance, standards-based messaging solution that provides e-mail, calendaring and scheduling across the Internet. It offers a high level of scalability-with proven support for 210,000 users on a single server. It can run on a single server or distributed across multiple servers to ensure scalability, reliability and high performance. It supports the leading e-mail, calendaring, Internet and security standards, and it runs on multiple platforms-ensuring flexibility and eliminating concerns about being locked into a single-vendor environment.

Novell also offers Novell NetMail XE, a simple and cost effective e-mail solution for small organizations that run Microsoft Windows* primarily. NetMail XE is reliable and easy to implement, and it supports standard Post Office Protocol (POP) and Internet Messaging Access Protocol (IMAP) clients, including Microsoft Outlook* and Netscape*. There is no need to install a directory or deal with the complexities of integrating Active Directory* and Exchange. NetMail XE leverages the Windows user registry and automatically enables existing users for Internet e-mail. For more information on NetMail XE, see the Novell NetMail XE Implementation Guide. You'll find it at: http://www.novell.com/info/collateral/docs/4621305.01/4621305.html

This paper provides a description of NetMail XE software, including an overview of its architecture, a detailed description of the agents that comprise the system, and a discussion of deployment on single- and multiple-server installations.

1 Source: AmeriStat (Population Reference Bureau) 2000.

Novell NetMail is a scalable, high-performance e-mail and calendaring system that is based on Internet-standard messaging, calendaring and security protocols. NetMail is built on Novell eDirectory™, which has proven itself in more than ten years of operation and is now in use by more than 420 million users worldwide. eDirectory permits nearly limitless scalability and has been tested with more than one billion objects in a single tree.

NetMail supports full eDirectory functionality, including NDS® (Novell Directory Services®) User and Group objects, NDS aliases (for login and addressing) and NDS organizational roles. Through NDS User objects functions, NetMail provides:

• Immediate effectiveness of changes in user-specific information (for example, forwarding configuration or quota changes).
• Disabling or temporary suspension of NetMail functionality for NDS User objects.
• Automatic creation of mailboxes for NDS User objects when an account is first accessed through a NetMail agent.

With NetMail, organizations enjoy the advantages that come with:

• Extensive scalability
• Single-point management
• Support for multiple access devices
• Support for popular e-mail, calendaring, Internet and security standards
• Ability to extend functionality
• Secure transport
• Platform independence
• Extensive monitoring, logging and reporting

Extensive scalability

NetMail scales to fit virtually any size environment, from 10 users to hundreds of thousands of users. Consequently, it meets the needs of many organization types, including large enterprises that want to expand e-mail and calendaring to deskless workers, Internet service providers (ISPs), application service providers (ASPs), institutes of higher education, school systems, government entities, and small and midsize businesses.

The multithreaded, multiprocessor NetMail architecture takes full advantage of available server hardware to achieve optimum performance. In a recent SPECmail2001 2 benchmark test, NetMail processed 1,050 SPECmail2001messages per minute-the equivalent of supporting 210,000 users-all on a single IBM* eServer xSeries 342.

Rather than simply throwing high-end server hardware at the SPECmail2001 test to ensure good results, Novell and IBM set out to determine how to optimize NetMail to best utilize the power of a single cost-effective server, such as the IBM eServer X342. The test was run using off-the-shelf hardware and software. Test team members combined their expertise to tune the NetMail system for the IBM server using standard NetWare tuning parameters. (No special software or patches were employed.) The benchmark results are available at the SPECmail Web site at www.spec.org. The results provide details on the NetWare parameter settings used to support this large number of users. NetMail customers can use this information to save time and money in tuning the NetMail system for their environments.

Single-point management

Administrators can manage NetMail user accounts, hardware and software configuration, and security all from a single point through eDirectory. They have a global view of user accounts, which simplifies user setup, administration and support. NetMail offers two administrator interfaces: NetWare Administrator (NWAdmin) and WebAdmin. Administrators who are familiar with NWAdmin can maintain and configure the system using the NWAdmin snap-in that is included with NetMail. The snap-in allows the administrator to create and modify NetMail objects from NWAdmin.

Administrators who prefer to perform administrative tasks through the Web can use WebAdmin, a browser-based interface that enables any time, anywhere Web-based access. With WebAdmin, all activities can be performed via SSL (Secure Sockets Layer) connections. SSL support makes it possible to maintain a NetMail system remotely and securely over the Internet.

Support for a variety of access devices

NetMail supports all browser-based access devices. Consequently, users can access their e-mail messages and calendars using whichever access device they prefer-a desktop or laptop computer, cellular phone, personal digital assistant (PDA), or even an Internet kiosk. NetMail also enables Palm OS* and Pocket PC* synchronization of e-mail, calendar and address book data from any network workstation containing the synchronization software and docking device. This extensive device support empowers the organization to extend its network to encompass all types of employees, from traditionally connected knowledge workers to deskless workers, and from employees who work from a fixed location to those who are highly mobile.

Support for popular industry standards

NetMail supports all popular e-mail, calendaring, Internet and security standards, including:

• Network Messaging Application Protocol (NMAP). A text-based IP protocol registered with the Internet Assigned Numbers Authority (IANA) at port 689. NMAP support permits NetMail agents to be distributed across multiple servers and use NMAP to communicate.
• Post Office Protocol Version 3 (POP3) and Internet Message Access Protocol Version 4 (IMAP4). Ensures compatibility with Novell GroupWise®, Microsoft Outlook and Outlook Express, Microsoft Exchange, Netscape Communicator, Eudora*, Pine, Pegasus Mail and other integrated and standalone e-mail clients.
• Simple Mail Transfer Protocol (SMTP). Ensures compatibility with e-mail servers on the Internet and most TCP/IP systems.
• Lightweight Directory Access Protocol (LDAP). Enables NetMail to perform lookups
  in eDirectory, Netscape Directory Server*, Microsoft Active Directory* or one of the many Web-based address books to locate organizations, individuals or any other resource within that directory.
• HyperText Transfer Protocol (HTTP). Permits users to access their mailboxes from any standard Web browser. Also permits system administrators to manage NetMail user accounts and messaging configurations from any standard Web browser.
• Security standards. Supports SSL 3.0 on all protocols, including POP3, IMAP4, SMTP and HTTP. Also supports the OpenSSL implementation of Transport Layer Security (TLS) in the SMTP agent, and Secure Multipurpose Internet Mail Extensions (S/MIME).
• iCalendar protocol. Provides a common format for openly exchanging calendaring and scheduling information across the Internet. Permits NetMail calendaring functions such as calendar events, tasks and notes to be used in conjunction with any other iCal-compliant application.
• Wireless Access Protocol (WAP) and Wireless Markup Language (WML) support. Provides support for wireless devices that are compatible with the WAP and WML standards. Enables mobile phone users who have a WAP/WML-enabled phone to access and manage their e-mail via a mobile phone-keeping in touch even when they don't have access to a computer.

Table 1 lists some of the many standards that NetMail supports.

Extended functionality

Novell has extended the functionality of NetMail beyond the services provided by SMTP, POP3 and IMAP4 protocols. Extended services include anti-spam, aliasing, autoreply, forwarding, LDAP, anti-virus, rules and calendaring services. Other custom services can be added using the IP-based NMAP protocol and other interfaces.

Secure transport

NetMail provides secure transport, permitting users easy access to mail over the Internet while ensuring privacy and protection of confidential information.

Platform independence

NetMail runs on all popular platforms including Linux, NetWare, Solaris and Windows XP/2000/NT. As a result, organizations can take advantage of the power of NetMail without introducing new platforms that might complicate the IT environment.

Extensive monitoring, logging and reporting

NetMail provides extensive monitoring, logging and real-time statistics reporting. NetMail also monitors the messaging server's performance. These capabilities enable administrators to stay on top of system operation and performance to ensure high quality of service for users.

2 Developed by the Standard Performance Evaluation Corporation (SPEC), SPECmail2001 is the first standardized benchmark that measures mail-server performance using a real-world workload. Details on the SPECmail benchmark results, are available at: http://www.spec.org/osg/mail2001/results/res2002q1/mail2001-20020312-00014.html

NetMail is built on a modular architecture that offers extensive flexibility without compromising system integrity. Product functions are strategically divided among several components, so an organization can install only those components it requires. Moreover, the components can be located on a single server or distributed across multiple servers based on usage and system resources.

NetMail components include:

• Messaging Server(s). Any server on the network that hosts one or more NetMail agents. The building-block architecture enables the organization to implement its entire messaging system on a single server or distribute it across multiple servers for higher reliability, faster performance and greater scalability.
• eDirectory. NetMail leverages existing eDirectory objects by adding NetMail-specific attributes to these existing objects. It also creates new NetMail-specific objects.
• NetMail agents. A series of executables that perform specific product functions. NetMail agents can all be run on the same server or distributed across multiple servers.

Tight integration with eDirectory

NetMail integrates tightly with eDirectory. It adds NetMail specific attributes to existing eDirectory components such as server objects, container objects and user objects. It also adds NetMail specific components, including:

• Internet Services container
• Messaging Server object
• Parent objects
• Templates
• Mailing Lists

NetMail uses eDirectory exclusively to store and look up user information and system configuration parameters. The only items that NetMail does not store in the directory are the e-mail messages themselves.

During the initial NetMail installation, the installation program extends the eDirectory schema to include NetMail related objects and attributes. Existing NDS objects, such as Container and User objects, take on new NetMail attributes.

Internet services container

Because it is part of NetMail, the Internet Services container differs from other NDS container objects. There can be only one Internet Services container per tree and, as the messaging system container, it contains only NetMail component objects.

Messaging server object

When NetMail is first installed, the install program automatically creates a Messaging Server object in the Internet Services container to represent the physical server on which the NetMail software is installed. The Messaging Server object is represented as a container with server attributes. It sets the messaging server properties and it "contains" all NetMail agents running on that server.

Parent objects

The install program automatically creates a Parent Objects container in the Internet Services container to provide a centralized location for Parent objects. NetMail permits the administrator to create Parent objects.

Parent objects allow administrators to manage agent services and user settings collectively for specific sets of users. This enables the administrator to subdivide a single messaging system into configuration subunits. For example, by creating separate Parent objects for each domain, administrators can manage every domain as if it were a separate messaging system.

The configuration options in the Parent object allow administrators to grant access to messaging services selectively. The administrator can enable or disable different agent services for each Parent object. For example, in an ISP environment, the system administrator could use Parent objects to give one hosted domain access to POP, 5 MB mailbox quotas and Spanish as the default language. The administrator could give another domain access to IMAP in addition to POP, with 10 MB mailbox quotas and a default language of German. This permits the ISP to bill for individual services and increased storage. Agents running on both distributed and standalone messaging servers dynamically look up the user's Parent object in the tree to determine what rights the user has to the service provided by the agent.

Parent objects can also be used to distribute administrative tasks, giving certain individuals the right to create, delete, modify or import user accounts in specific Internet domains. For example, in a corporate environment, the system administrator could use Parent objects to permit administrative assistants to create user accounts for their respective departments.

NetMail agents are a series of executables that perform specific product functions. The agents have plug-and-play versatility, that is, they can be combined in a variety of configurations and still maintain the functionality of a single, integrated messaging system. Table 2 provides a list of NetMail agents.

NMAP Agent

The NMAP Agent is the heart of the NetMail system. It is responsible for message processing and delivery as well as for the physical mailboxes and message queues. The NMAP Agent:

• Provides mailbox access to other agents.
• Moves messages through the queuing system.
• Notifies other agents when they need to take action on a message.
• Enforces disk quotas (configurable globally or at the user level).
• Maintains only a single copy of a message sent to multiple users to conserve disk space.

NMAP acts as a traffic cop for messages, from the time a message enters the message queue until it is delivered to the user's mailbox or passed off for delivery via the Internet. The NMAP Agent determines what other agents need to process a message and in what order. To ensure fast performance and high scalability, the NMAP Agent is multithreaded and can simultaneously process as many messages as memory allows.

NMAP is the only NetMail agent that performs file access. All other NetMail agents gain access to mailboxes and message queues through the NMAP Agent using the NMAP protocol.

Because it is core to NetMail, all NetMail systems must have at least one NMAP Agent. Additional NMAP Agents can be added to any server in the directory tree. This is typically done to distribute mailboxes over multiple servers or to move mailboxes closer to remote users.

The NMAP Agent also permits control of bounced messages to prevent spammers from using bounced messages to disguise spam. Spammers sometimes falsify the From: field in their message so the resulting bounced messages go to a mail server other than their own. As a result, the server that owns the domain specified in the From: field is inundated with thousands of bounced messages in a short period of time.

The NMAP Agent permits the administrator to set a threshold for the number of bounced messages it will process within a set time period. If the number of bounced messages exceeds the defined threshold, the messages are deleted instead of being processed.

SMTP Agent

The SMTP Agent is responsible for receiving mail and sending mail to remote mail systems over the Internet. This agent can also be used by standards-based mail clients to drop off messages.

The SMTP Agent streams incoming messages to the NMAP Agent, and the NMAP Agent notifies the SMTP Agent when queued messages are ready to be sent to remote systems. (A single SMTP Agent can be used to pick up outbound messages from multiple NMAP Agents.)

The SMTP Agent supports Extended SMTP (ESMTP) and SMTP-after-POP authentication. In ESMTP authentication, the e-mail client must authenticate through SMTP-Auth before the SMTP Agent will relay its messages to remote recipients. In SMTP-after-POP authentication, users cannot send remote messages through the SMTP Agent until they have first authenticated with the messaging system via their POP3 or IMAP4 client.

NetMail SMTP Agent has several features for preventing unsolicited bulk e-mail (spam or UBE). It can be set up to refuse incoming messages from IP addresses that are:

• In the ranges configured by the administrator.
• Listed in the Realtime Blackhole List or other similar services such as ORBS, Spamcop and SPEWS.
• Not resolvable via Domain Naming Services (DNS).

The SMTP Agent can also be set up to relay messages only if:

• The sender's IP address is on a list configured by the administrator.
• The sender has authenticated through SMTP-Auth.
• The sender has recently authenticated through POP3 or IMAP4 (SMTP-After-POP).

The SMTP Agent supports multiple
Internet domains on a single messaging system. This capability permits hosted domains to have separate address books and separate message stores-a feature that is especially important for service providers.

POP3 and IMAP4 Agents

The POP3 and IMAP4 Agents provide support for GroupWise, Microsoft Outlook and Outlook Express, Microsoft Exchange, Netscape Communicator*, Eudora, Pine, Pegasus Mail and other integrated and standalone e-mail clients. This gives people the flexibility to use any e-mail clients they choose-even keeping their current e-mail clients if they wish.

Modular Web Agent

The Modular Web Agent provides the browser-based interface to the NetMail mailbox and calendar. It is customizable to provide maximum flexibility to users and administrators. Two HTML client interfaces are included with NetMail: WebMail and WebAccess. NetMail also includes the tools for creating additional HTML interfaces.

The WebMail interface is patterned after the Novell Internet Messaging System™ (NIMS™) 2.5 mail client interface. The WebMail client provides standard mail client functionality, including:

• Reading and sending messages.
• Attachment support (sending and receiving).
• Personal address book.
• LDAP address lookup.
• Mailbox folder management.
• Quota monitoring.
• Support for single- and double-byte language encoding.
• User interface in multiple languages.

Additionally, administrators can give users access to self-administration features through the WebMail interface. Self-administration features include:

• Changing the user's eDirectory password (the NetMail and eDirectory password are the same).
• User interface configuration (colors, character sets and other preferences).
• Configuration of automatic message forwarding and custom message reply.
• Proxy configuration to pull messages from other accounts.

The WebAccess interface provides all the features of WebMail plus:

• Integrated help.
• A calendar capability that permits users to maintain a calendar of appointments, create and accept appointments, maintain notes and manage tasks.
• A delegation capability that permits administrators to use the WebAccess interface to give selected users access to NetMail administrative functions such as adding, modifying and deleting user accounts.

The Modular Web Agent includes several submodules that enable various client functions:

• IMS Mail Module provides mail and address book functions.
• IMS Calendar Module enables the WebAccess calendar features including appointments, tasks and notes.
• IMS Preferences Module allows users to set or change preferences using Preferences in the WebMail template, or the Options screen in the WebAccess template. Settings include:

  - Password
  - Reply-to address
  - Default character set
  - Preferred language
  - Web template

• IMS Task Management Module enables delegation of administrative functions such as creating, modifying or deleting users.

Because the administrator can modify the user interface templates, the administrator has substantial control over what users can and cannot see and do through the user interface. As a result, the administrator can limit the scope of users' access to Modular Web Agent services.

Calendar Agent

The Calendar Agent provides automatic status tracking information for scheduled appointments, tasks and notes. When a user schedules a calendar event, the Calendar Agent processes all Accept and Decline responses and automatically updates the event's status information in the event organizer's calendar. If the administrator chooses not to run the Calendar Agent, users receive
iCal status messages in their inbox.

Address Book Agent

The Address Book Agent provides an LDAP server for resolving address lookups against eDirectory. The agent runs lookups against eDirectory, searching for users matching the LDAP search criteria. Information returned about each user depends on the user's privacy level that is set in Preferences/Options.

The Address Book Agent answers requests at a high rate. To speed LDAP queries, the agent maintains an index of all users in its supported NDS contexts, making it possible to use the agent with the address type-ahead feature of many popular e-mail clients.

The agent can also be configured to automatically create a publicly accessible LDAP Data Interchange Format (LDIF) file of all user information (except for information or accounts protected by NetMail privacy settings).

Forwarding/AutoReply Agent

The Forwarding/AutoReply Agent permits automatic reply to all incoming e-mail. It also permits e-mail to be forwarded automatically to other e-mail addresses. A user may specify a custom auto-reply message that is returned to senders of all incoming e-mail, and one or more addresses to which messages are to be automatically forwarded. For example, the forwarding feature permits the delivery of Short Message Service (SMS) messages to cellular phones and pagers while at the same time delivering the messages to a user's mailbox.

The Forwarding/AutoReply Agent is independent of any e-mail client. Although users configure mail forwarding and autoreply messages using the Modular Web client, the agent functions independently of any e-mail client, including the Modular Web client. That's because each user's forward and autoreply information is stored in the NDS User Object. As a result, NetMail can handle forwarding and autoreply messages for users of POP3, IMAP4 and Modular Web clients independently of the clients.

Rule Agent

The Rule Agent executes rules defined in the Modular Web Agent. Rules can be defined for moving, copying, deleting or forwarding mail based on From:, To:, CC:, Subject or Body. For example, a rule can specify that all messages containing "Marketing" in the subject and are from "jjones" are to be moved to the "Marketing Review" folder.

Like the Forwarding/AutoReply Agent, the Rule Agent is independent of any e-mail client. Although users configure rules using the Modular Web client, the agent functions independently of any e-mail client, including the Modular Web client. That's because user's rules are stored in the NDS User object. As a result, NetMail executes the configured rules whether the user opens messages in a POP3, IMAP4 or Modular Web client.

Mail Proxy Agent

The Mail Proxy Agent permits users to configure their accounts to consolidate messages from up to three external POP3 or IMAP4 messaging systems into their NetMail mailbox. Either the administrator or the user can set user preferences to configure which hosts/accounts the Mail Proxy Agent accesses.

Unlike some messaging systems in which messages are received as attachments, the Mail Proxy Agent places messages in the NetMail mailbox with no change to the header. Consequently, the NetMail mailbox appears as the final destination.

In addition to consolidating messages into a single mailbox for the convenience of the user, the Proxy Agent can also facilitate the transition from an old messaging system to NetMail.

Alias Agent

The Alias Agent allows a network administrator to configure one or more user aliases for a single NDS User object. If configured to do so, NetMail pulls the user account information directly from eDirectory and generates the aliases automatically.

For example, when setting up the system, the administrator can use the Alias Agent to generate names in the form FirstName.LastName. To the outside world, e-mail addresses for users within the organization appear as FirstName.LastName@YourDomain.com. (Of course, NDSLogin@YourDomain.com is also a valid address.) With aliasing, users still authenticate to the messaging system using their regular NDS login names, so there is no confusion to users, and the administrator does not have to create an alias manually for every user.

The formats automatically provided by the Aliasing Agent are:

• FirstName_LastName@domain.com (bob_smith@domain.com)
• FirstInitialLastName@domain.com (bsmith@domain.com) (This format is limited to eight characters before the "@".)
• FirstName.LastName@domain.com (bob.smith@domain.com)
• FirstName.MI.LastName@domain.com (bob.w.smith@domain.com)
• FirstName_MI_LastName@domain.com (bob_w_smith@domain.com)

An administrator may also create custom e-mail aliases. For example, feedback@domain.com can be set as an alias of any particular NDS User or supported object.

Anti-virus Agent

The Anti-virus Agent integrates with McAfee NetShield*, Computer Associates InoculateIT/eTrust* and Symantec CarrierScan* (also known as Symantec Scan Engine 3.0) virus engines to provide virus scanning on all messages handled by NetMail. All messages are scanned regardless of whether they originate from external addresses or are internal messages that never leave the NetMail system.

Anti-spam Agent

The Anti-spam Agent allows the Postmaster or NetMail administrator to create a blackout list of undesirable e-mail domains and addresses. NetMail does not accept messages sent from domains and e-mail addresses contained in the blackout list.

List Server Agent

The List Server Agent provides List Server functionality in a NetMail environment. It supports a range of functions, from two-way, fully interactive discussions to one-way lists that deliver announcements, newsletters and advertising without allowing responses. Typically, users subscribe to list server mailing lists via e-mail.

The List Server Agent works in conjunction with NDS Mailing Lists and standard e-mail Mailing Lists. NDS based mailing lists are built from NDS Container, Group or User objects. Standard mailing lists are e-mail based and require the full e-mail address of each subscriber.

Connection Manager

The Connection Manager keeps track of authenticated users. When a user logs in via POP3 or IMAP4, the POP or IMAP Agent grabs the client's IP address and sends it to the Connection Manager Agent. The Connection Manager Agent then keeps track of the IP address for a designated time period (the default is 15 minutes). NetMail considers a user to be authenticated for as long as the Connection Manager maintains his or her IP address.

Like traditional e-mail systems, NetMail can run on a single server-with all agents running on the same server. NetMail has demonstrated its ability to support up to 210,000 users on a single server.

In addition, and unlike traditional e-mail systems, NetMail is not limited to an environment in which all messaging system services must run on the same server. NetMail agents can operate across multiple servers, and communicate using the NMAP protocol. When combined with the distributed nature of Novell eDirectory, the NMAP protocol allows NetMail agents running on different servers (even on different platforms) to operate as if they were on the same server.

Flexible configuration

Because it can operate in both a single server and a distributed environment, NetMail offers considerable flexibility in configuration.

Single-server configuration

This is the simplest NetMail configuration because the NetMail messaging server is the only server in the NDS tree. All NetMail components are installed on the same server (see Figure 1). This configuration is typically implemented by small to medium organizations in which NDS is not used for other network services.

Single messaging server LAN

In this configuration, more than one server exists in the NDS tree, but only one server is needed to provide messaging services (see Figure 2, previous page). This configuration is typically implemented by small to medium size organizations in which NDS is also used for other network services

Multiple standalone messaging server LAN

Multiple single-server, standalone systems can be run on the same network (see Figure 3). Each messaging server is assigned to a different domain and functions as an independent messaging system. This configuration is typically used in medium to large enterprises that have several separately managed information technology (IT) departments and Internet domains or subdomains

Multiple distributed messaging server LAN

This configuration implements a messaging system in which message traffic exceeds the resources of a single server, but all messaging servers share the same high-speed network (see Figure 4). This configuration is typically used in ISP, ASP, or medium to large enterprise LAN environments.

Multiple messaging server WAN

This configuration consists of a network in which the messaging system connects different geographical locations, but users still receive messages at the same Internet domain (see Figure 5). This configuration is typically implemented in government and enterprise organizations that have one or more remote locations.

Building fault tolerance

An organization can optionally increase NetMail fault tolerance by implementing redundancy and failover support at either or both of two levels: the application level and the hardware level.

Application-level clustering

Application-level clustering consists of duplicating critical mail services on multiple servers. Because of the highly modular NetMail architecture and eDirectory replication, critical services can be run simultaneously on multiple servers, each providing the same service to users. If one server fails, alternate servers continue to provide services to users for continuous availability. This provides fault tolerance for most mail services at the application level. The only NetMail component that cannot be cloned at the application level is the message store.

Hardware-level clustering

With hardware-level clustering, servers are connected in a group. If a server in the group fails, automatic failover to another server in the group occurs. Consequently, operation continues with little or no disruption to users.

For example, only one NMAP Agent should be deployed to service a given user context and its associated mailboxes, yet NMAP is a critical service and needs to be protected against server failure. Hardware level clustering allows the NMAP service to failover to another server so users can still retrieve their mail in the event of a server failure.

Advantages of a distributed NetMail system

Organizations can gain several important advantages by distributing NetMail across servers. These advantages include:

• Increased fault tolerance for higher reliability. Service redundancy and failover support can be implemented at the application level and at the hardware level to shield critical processes from a single point of failure.
• Faster performance for increased user satisfaction. The organization can provide round-robin DNS entries for redundant servers to distribute the workload evenly across servers. Distributing the workload in this way results in faster performance.
• Greater scalability to support a growing number of users and an expanding message volume. An organization can start with a single server installation and migrate to a distributed environment as workload increases. Instead of replacing a server with a bigger server, the IT staff simply adds servers. There is no need to reinstall the system, and NetMail maintains all configuration information. As a result, the migration to a distributed environment is simple, straightforward and non-disruptive.

Supported by licensing and platform flexibility

NetMail is licensed on a per-mailbox basis rather than on a CPU or platform basis. As a result, when moving from single to distributed mode the organization need not purchase additional licenses or copies of NetMail, as long as the total number of licensed mailboxes is not exceeded.

There is no need to purchase separate NetMail versions for different operating systems. NetMail ships with versions for all supported operating systems on a single distribution medium. As a result, the organization can configure NetMail in a mixed environment as a single, distributed system. For example, the organization can run some agents on NetWare and others on Linux, Solaris and Windows-without additional cost.

Attractive in large message environments

Distributed message servers are most often used in larger message systems such as those run by ISPs, ASPs and enterprises with multi-LAN environments. Because of message traffic volume, performance requirements or the local distribution of the network, these organizations typically require multiple messaging servers to provide the load balancing, fault tolerance and speed required to service their customers. The ability to operate across multiple servers and platforms makes NetMail an excellent choice for these organizations.

IT professionals are under pressure to provide e-mail and calendaring services to a rapidly expanding number of users. Supporting a large user base and a growing message volume has required considerable time, effort and money. Traditional e-mail and calendaring systems require the deployment of a large number of servers to support the thousands of users that many organizations have to service. Moreover, traditional systems don't offer the scalability, reliability, performance or affordability that large enterprises, colleges and universities, school systems, ASPs and ISPs, and other organizations need to ensure the availability of these essential tools to their users.

With its directory foundation and advanced architecture, Novell NetMail can support hundreds of thousands of users on a single server without sacrificing performance. What's more, NetMail can be distributed across multiple servers to ensure continuous availability and a high level of scalability.

With NetMail, organizations can extend e-mail and calendaring across the enterprise and beyond, while simplifying management, minimizing support requirements and reducing costs.

- Novell home page
- NetMail home page
- NetMail Cool Solutions page
- System requirements
- SPECmail benchmark results
- NetMail SDK-Leading Edge 162