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?
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.