SearchEnterpriseLinux.com readers have lots of questions about the various open source and Linux-based e-mail systems...
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available today. To get some of them answers, we caught up with our resident open source messaging expert, Julie Hanna Farris, who is also the founding Chief Strategy Officer (CSO) of Linux messaging company Scalix Corp.
One of the two people on the IT staff (I'm the other one) for my small business thinks that we should check out Smartmax and Qmail. Right now, we're using Microdollar, and we could sure use the money we spend on that for other things if we could get cheaper e-mail. I've read the blurbs on Smartmax and Qmail. How do they really work in the field? My organization has 50 people now and is growing.
Farris: It's not easy running an IT department these days. There is constant pressure to increase productivity and innovate while cutting costs. The e-mail system, which frequently has a high total cost, is a common target for cost control. While I don't have enough information to determine whether switching to Qmail or Smartmax will ultimately save you money, Linux-based e-mail can be a very affordable, secure and reliable alternative. Here are ways to think about your e-mail cost structure and how to cut costs.
Start with end user productivity: As you look to reduce costs, you will want to ensure that user productivity and functionality is not negatively impacted. Smartmax and Qmail don't support the full range of functionality available in Outlook. If your organization uses calendaring and scheduling, public folders and the advanced features in Outlook, a move to one of these products will mean significant losses in functionality. There are Linux e-mail alternatives that support the full set of functionality that comes with Outlook, however. There are two ways to determine this: Whether the Linux mail system supports MAPI in native mode and if the Linux mail system supports Outlook running in Workgroup mode.
You can reduce user-related costs by eliminating system downtime. There are many Linux e-mail alternatives that provide superior reliability and less downtime.
Finally, do not forget to account for the cost of e-mail ecosystem components that improve system security and user productivity. These items include anti-virus and anti-spam software, directory and identity management software and system monitoring tools. A Linux mail system that supports a broad variety of open source tools such as Spam Assassin, ClamAV, Nagios, LVM and OpenLDAP can reduce the cost of e-mail by as much as 30% to 70%.
What is the difference between Postfix and SendMail? Is one better than the other for certain things?
Farris: SendMail and postfix are message transfer agents (MTAs). An MTA is a program responsible for receiving, routing and delivering e-mail. MTAs receive e-mail messages and recipient addresses from local users and remote hosts; perform alias creation and forwarding functions; and deliver messages to their destinations. The most obvious difference between these two MTAs is architecture. Postfix uses a modular approach and is composed of multiple independent executables. SendMail has a more monolithic design utilizing a single always running daemon. SendMail and postfix each have large installed bases and perform well for businesses of many sizes. They are direct replacements for each other. Some will claim that one or the other is more secure, faster or easier to administer. There is a wealth of good information available online to enable you to dig deeper into these claims.
My company has used Exim, which gives us good control over some 23,000 mail boxes. Exim allows our use of seven separate domains on the same server to be maintained while we consolidate the customers. My company is growing quickly, however. Is Exim going to scale well? Have you heard anything about how Exim performs for larger companies? How does it compare feature-wise to other software program?
Farris: It sounds like you might be an Internet Service Provider (ISP) because few corporations support the number of mailboxes, domains and growth rate that you mention solely with a mail transfer agent (MTA) like Exim. An MTA is a program for receiving, routing and delivering e-mail. MTAs differ from messaging servers as they do not have message storage, directories, address lists, contact management, calendaring and other features. Exim was developed at the University of Cambridge for use on Unix systems connected to the Internet. Like most MTAs, Exim has a good reputation for efficiently delivering mail and for scalability, like SendMail and postfix. Commenting on specific Exim scalability for larger organizations is difficult due to the variables that affect performance. Feature-wise, it is comparable with other MTAs. For more information, www.exim.org contains mailing lists where users actively discuss these and other topics.
We use Exchange Server as our mail server and want to migrate to a Linux mail server, either SendMail or Qmail. All the users' mail is on Exchange Server. Is there any way that mail on Exchange can be shifted to a Linux mail server easily without losing data?
Farris: It is definitely possible to migrate e-mail on Exchange to a Linux e-mail server. The degree of difficulty depends on multiple factors, including:
- Organizations moving from Exchange will likely have a large store of user e-mail, calendar, public folder, directory and other data to migrate. The longer the e-mail system has been in use, the greater the number of users, and the more complex the Exchange configuration, the longer it will take to complete the migration process. Industry averages for migration range from a few days or weeks for a simple migration to several months for a complex migration. What is interesting to note is that it can also take quite awhile just to upgrade from one version of an e-mail system to another.
- Not all Linux e-mail servers are equal. It is important to understand some key issues, such as whether the e-mail server can co-exist with Exchange for an extended period of time (so that a flash cutover is not required). Also, to what degree can messages and other data be faithfully retained (so, e.g., when e-mail is migrated, a user can continue to reply to e-mail such that the prior sender's e-mail address does not need to be retyped).
The advantages of Linux e-mail include: reliability, security, performance, cost-efficiency and freedom from licensing and technology lock-in. It will be important to select an e-mail system that supports the level of functionality your end users rely on in your current Exchange environment. Other considerations:
- High fidelity co-existence with Exchange and your existing directory, eliminating the need for a flash-cut migration to the next system. Specifically, this means retaining fidelity of messages, calendar interoperability, public folder sharing between Exchange and the next system.
- Minimize user impact in the migration process. This means transparent migration of the user's mailbox and little or no downtime for end users.
- Flexibility in your migration process. No two companies are alike, so you should make sure your supplier can support a migration accommodates your needs and timetable.
Is Thunderbird a Web-based e-mail? Or, is it a mail server like MS Exchange?
Farris: Thunderbird is an open source and platform-independent e-mail and newsgroup client available from Mozilla.org. Mozilla is the same organization that develops the popular Firefox Web browser. Thunderbird doesn't run on Firefox; rather, it is a stand-alone e-mail client much like Outlook Express, Novell Evolution or Kmail. Thunderbird is available on several platforms, including Linux, Windows, UNIX and Mac OS X computers and supports the POP and IMAP e-mail protocol standards. First available in December 2004, Thunderbird is particularly innovative with its client-side junk mail filter. For more information about Thunderbird, visit the Thunderbird Website.