This tip provides an intro to open source sendmail and discusses the pros and cons of using it. I'll also offer a way to implement sendmail that might appeal to those who think that bringing in Sendmail would be too much work.
First, what is Sendmail? Simply put, sendmail is a mail transfer agent (MTA) and is also known as a mail server. MTAs are a fundamental piece of the Internet, providing e-mail capability to users. E-mail is the killer application of the Internet, and every e-mail message that gets sent, whether profound or profane, requires an MTA.
MTAs accept mail from any e-mail client that knows how to talk to them via simple mail transfer protocol (SMTP), forward e-mails to the appropriate location for each e-mail's recipient and allow e-mail clients to retrieve e-mail to be read. Simple, eh?
Conceptually, yes. Practically, no.
E-mail is the most heavily used application in the enterprise. There are a host of issues that accompany e-mail these days: spam, viruses, malware and the like. So an effective e-mail product needs to be functional, scalable and extensible.
Sendmail is the granddaddy of e-mail software. It was developed in the early days of Unix and is the mail server of choice in thousands, if not hundreds of thousands, of locations. If your organization is looking for a time-tested mail server, you should consider Sendmail.
However, you should be aware of some of its drawbacks.
First, sendmail is focused solely on e-mail. Many organizations use Microsoft Exchange because it offers an integrated suite that provides e-mail, along with contact management and shared calendaring. For them, having a single product that delivers all of that functionality is convenient. Open source Sendmail does not offer an integrated product that provides contacts and calendaring. That's not to say that Sendmail can't be tweaked to support these functions -- but it requires installing other programs and configuring them to work with sendmail.
This goes for antivirus and antispam functionality as well. There are excellent programs available that integrate with Sendmail -- but you'll have to do the integration and configuration.
Speaking of configuration, sendmail has a reputation for being difficult to configure. It's not clear if that reputation is deserved, but it is by no means an install-and-forget product. Fortunately, there are excellent reference books available to walk you through the process.
What about support? E-mail is pretty important, after all. What resources are available to help you keep it up and running? Check out sendmail.org, and you'll find a long list of community resources: Web pages, mailing lists and forums.
What if you don't want to rely upon those mechanisms and want commercial support? There are many companies that provide commercial support. For one thing, open source sendmail is bundled with many Linux distributions, so support is available through commercial distribution companies.
As I mentioned earlier, there is a commercial provider of sendmail called Sendmail Inc.. This company sells a commercial Sendmail that comes pre-integrated with a lot of requisite functionality and also provide support for their product.
What if the whole install and administration effort just seems like too much work? Well, there is an alternative. Several companies sell e-mail appliances based upon Sendmail. Some examples are Symantec, and InterShield. They come packaged in a 1U form factor, ready to be installed in a rack and plugged into your network. All of the hard work of configuration is already done, leaving nothing more than user account setup left to do.
Golden's Rule: So, the question, "Sendmail in the enterprise: Why or why not?" might be restated, "Sendmail in your enterprise: What or how?" It comes in so many versions that one will probably work for you. You just need to decide which version makes sense for your company.