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Messaging tips for admins, part 1: Choosing the right e-mail server

This two-part tip collects some of her recent advice. In part one, Julie gives advice for choosing the right e-mail server in different circumstances.

As a 15-year veteran of the messaging market, Julie Farris is familiar with the enterprise e-mail trenches. At Bell South Telecommunications, she pioneered the design and deployment of one of the world's largest and most advanced enterprise scale networks for distributed messaging and groupware. As a site expert on, Julie helps our readers deal with their own enterprise messaging challenges. This two-part tip collects some of her recent advice. In part one, Julie gives advice for choosing the right e-mail server in different circumstances. In part two, she tackles other tough decisions -- including whether or not Lotus Notes can be useful in a Linux environment.

I am going to design a network that will connect one main office (100-200users) and two branch offices (50-100users/office). Our OS will be SuSE Linux. Some services that will run on the network are e-mail, office management software, human resource management software, accounting management software, database transaction between main and branch offices using Oracle 10i and Internet access through the main office using ADSL connection. What would be a good server and client e-mail choice?

Farris: Machine sizing and network design are part science, part black art. The number of employees in the various locations is a major factor in designing the solution, but other factors need to be considered as well.

For example, If your IT and corporate strategy involves centralization or server consolidation, you will want to host all mail users on a single mail server. This has many advantages, including less cost and complexity -- specifically, less hardware and configuration complexity to purchase, install and maintain your e-mail system. Such a strategy, however, may require you to increase the network bandwidth between remote and HQ offices to ensure that end user performance is adequate. This is greatly dependent on e-mail client choice and means of connectivity. For example, POP/IMAP based clients will not be as bandwidth sensitive as MAPI-based clients, like Microsoft Outlook. Ultimately, the centralized configuration will be the lowest in cost.

Alternatively, if each of the three offices maintains a high degree of autonomy and you have IT staff at each location, you could host a mail server at each office. Because the decentralized design requires additional hardware and IT effort to manage, this is typically a more expensive configuration to acquire and more complex to maintain. It could offer higher perceived performance for each group of local users, if you don't have the ability to deploy the network bandwidth required to support a centralized server.

Some of the other factors that go into your design include the amount and nature of the traffic between the various clients and servers, the amount and nature of traffic between the three offices, the cost for network bandwidth, growth plans and IT skills present in the remote offices.

You'll want to confirm machine sizing with your mail server software vendor. Many, but not all, Linux-based mail servers can support 500 "office workers" on a single server-class computer configured with sufficient memory and disk storage. I'd recommend evaluating Sendmail, Cyrus IMAP server for basic e-mail, and Groupwise, Notes/Domino, Bynari, Scalix and OpenExchange for more advanced e-mail and collaboration capabilities. It will be important to understand your end-user needs in terms of functionality as you perform your evaluation.

With e-mail clients, there are a number of choices for Linux, Windows and other desktop systems. A good e-mail client is one that is compatible with mail server software, supportable by IT and familiar to end users so that additional training isn't required. Microsoft Outlook is frequently used on Windows desktops. Novell Evolution and Mozilla Thunderbird are popular choices for Linux desktops. Several Web e-mail clients now rival the features and performance of full desktop e-mail applications, and are worth consideration. E-mail clients and Web browsers can usually run on minimally configured desktop computers.

 My company is using the free, open source sendmail, but we are thinking of making a change because the company has grown from 15 to 290 employees. Sendmail has been difficult to configure but is also very flexible and works pretty well for us. Could you tell me: Is sendmail really viable for a rapidly growing company? (We expect to have 350 employees by the end of the year.) Is sendmail vulnerable, security-wise? Would there be an advantage to using the version from SendMail, Inc.? Would qmail or postfix be a better option? Or, are there low-cost commercial options? If we continue to use sendmail, do you have any advice or best practices for scaling and maintaining it?

Farris: Sendmail is a mail transfer agent (MTA) which means it excels at routing mail across the Internet. Sendmail is broadly distributed with Linux and Unix operating systems, which is the main root of its popularity. Without purchasing or installing any additional products, an organization can send and receive mail amongst themselves and others via the Internet. Sendmail is readily secured through relatively common integrations with anti-spam and anti-virus solutions.

Rather than debate which MTA you should use, you may want to explore a different question: Should you be using a full-functioned mail server instead of an MTA? If you see value in features such as mail account management, calendaring, scheduling, contact management, corporate directories and centralized mail storage, you are ready to step up to a messaging server.

There are a number of capable enterprise-ready messaging servers available on Linux, including the commercial product from SendMail Inc., Novell Groupwise, IBM Lotus Domino and Scalix. Open source solutions include the Cyrus IMAP server managed by Carnegie Mellon University. Each of these products should be compatible with your existing sendmail MTA while offering additional functionality and simplified management.


Continue reading Part 2 of this tip.

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