Keeping in line with Backspin's\u00a0current focus on anti-spam technology\u00a0and the fact that we just received an update of a product that we've meant to review for some time, this week we'll look at an established mail server with new anti-spam features. The product is IMail from Ipswitch, and the release is Version 8.1. We started using this product a couple of versions ago and have been impressed with its stability and features.IMail supports all the standard e-mail protocols - Simple Mail Transfer Protocol, POP3 and Internet Message Access Protocol 4 - and also includes Lightweight Directory Access Protocol Revision 3, Finger, Whois and password servers.IMail offers Web Messaging with spell-check, address book and multiple attachments, and Web Calendaring to keep schedules, appointments, task lists and date reminders. Both Web Messaging and Web Calendaring are based on customizable Web templates so that you can provide messaging and calendaring for your organization. Web Messaging and Web Calendaring also support Secure Sockets Layer connections, and you can choose whether users must use SSL, choose to use SSL or not use SSL at all.IMail supports multiple domains (five for the Small Business Edition and unlimited for the Professional version), so you can host mail for multiple organizations or groups on a single server. Ipswitch claims impressive scalability to more than 100,000 accounts on a single server and support for more than 1 million messages per day.User account information can be taken from the Windows NT\/2000\/XP user database, or IMail can use its own database or an external Open Database Connectivity (ODBC) database. The advantage of using ODBC is that user information can be extracted from Microsoft Access, SQL or Oracle databases, which makes it easy to integrate the server with customer billing, enrollment or other support systems.The IMail server includes e-mail lists and supports mail delivery rules so messages can be can filtered based on the content. IMail also can route messages to alphanumeric pagers, and Ipswitch offers an add-on to send e-mail to fax machines.IMail server management is very good. You can control the various services using the IMail Administrator program or through the administrative Web interface. Part of the management system is a monitor service that watches all the IMail services, and restarts and reports on services if they stop.As you might have noticed, many of these features point to one of the key positioning issues of IMail: It is designed to scale to the demands of enterprise or ISP use.The anti-spam features include Real-time Blackhole Lists (RBL); MAIL FROM verification; Reverse DNS Lookup to verify the IP address of sending servers (this prevents spoofing); EHLO\/HELO domain validation (verifies that the sending mail server domain exists in DNS); kill lists (blocked e-mail addresses and domains); trusted IP address; Bayesian statistical filters; phrase filtering; white lists; and sophisticated HTML filtering that detects nested tables, hyperlinks, images, scripts, invalid tags, mailto links, deceptive URLs and embedded comments.The RBLs are third-party services that list the domain names and IP addresses of known spammers. IMail comes with five free third-party RBLs and you can add additional lists as required.When a message isn't blocked by the blacklist or is passed by the whitelist, its authenticity is tested first by checking against the RBLs and then by other various DNS-based tests. Finally the content filters are applied and suspected spam is deleted, forwarded to another account, or an X-header is added.X-headers are custom headers added to a message that can contain any data and, in the case of IMail, their names always begin with X-IMAIL-SPAM- , followed by the condition that makes them suspect. This then lets e-mail clients or other anti-spam tools identify potential spam message for further action.We love this product. It is robust and has excellent features. There's a free version called IMail Express, which supports a single domain and five user accounts but omits lists and a few other features. There are also two charged-for versions: IMail Small Business, which costs $695 (maximum five domains, 10 lists but unlimited users), and IMail Professional, which costs about $1,500.We're just starting to test IMail's anti-spam features so we'll let you know what impact they make in the future.In the meantime, send a message to email@example.com.