Server-based software
Server-based software can run on your mail server or on a separate machine. It checks for e-mail from known spammers and filters messages based on e-mail headers, and transport information, and content.

Clearswift MailSweeper for SMTP
Works with: Microsoft Exchange, SMTP
Notable features: Analyzes incoming and outgoing e-mail at the Internet gateway. Screens e-mails based on source, content, and destination. LDAP integration. Policy management for senders and recipients.

Clearswift MailSweeper for Exchange
Works with: Microsoft Exchange
Notable features: LDAP integration. Policy management for senders and recipients. Removes inappropriate attachments. Manages undesirable file types.

Clearswift MailSweeper for Domino
Works with: Lotus Domino
Notable features: LDAP integration. Policy management for senders and recipients. Removes inappropriate attachments. Manages undesirable file types.

CMS Praetor for Lotus Domino
Works with: Lotus Domino
Notable features: Uses real-time blackhole lists to identify known spam domains (requires subscription to MAPS). Rules wizard permits construction of administrator-defined custom filters.

CMS Praetor for Microsoft Exchange Server
Works with: Microsoft Exchange
Notable features: Uses real-time blackhole lists to identify known spam domains(requires subscription to MAPS). Rules wizard permits construction of administrator-defined custom filters.

CMS Praetor for SMTP
Works with: SMTP
Notable features: Uses real-time blackhole lists to identify known spam domains (requires subscription to MAPS). Rules wizard permits construction of administrator-defined custom filters.

Elron IM Message Inspector
Works with: Lotus Notes, Microsoft Exchange
Notable features: Analyzes the context of messages and ranks their relevance. Built-in Web-based reporting. Anti-virus software available. (Download demo)

GFi MailSecurity for Exchange/SMTP 7
Works with: SMTP, Microsoft Exchange
Notable features: Content checking rules engine. Quarantines messages with macros. Approval of quarantined messages via moderator client or e-mail client.

GFi MailEssentials for Exchange/SMTP
Works with: SMTP, Microsoft Exchange
Notable features: Analysis of e-mail content and header information. Checks for domain validity. Archives inbound and outbound e-mail. Upgrade available with virus protection.

Lyris MailShield Server
Works with: Windows 2000, Solaris, Linux, FreeBSD
Notable features: Links to MAPS or ORBL. E-mail filter management via Web browser. Integrates with third-party anti-virus products.

Mail-Filters SpamCure
Works with: Windows 2000
Notable features: Mail filters. New spam signatures incorporated into filters. No anti-virus features.

Marshal MailMarshal
Works with: Lotus Notes, Microsoft Exchange, SMTP
Notable features: Archive unpacking: Scans multi-level .zip files. Supports MAPS. Usage reports. LDAP support. Supports third-party anti-virus products.

NAI WebShield SMTP
Works with: SMTP
Notable features: Remote management via SMTP client. Auto virus definition updates. Statistics on number of e-mails scanned, infected, and filtered for content.

SurfControl SuperScout E-mail Filter for SMTP/Exchange
Works with: SMTP, Microsoft Exchange
Notable features: Transmits non-essential e-mail after business hours. User-customizable keyword dictionaries. Remote administration.

Sybari Antigen 6.2 for Microsoft Exchange
Works with: Microsoft Exchange
Notable features: Multiple scan engine support. Scans multi-level .zip files. SMTP and M: drive scanning. Deleted files replaced with customizable text file.

Symantec Mail-Gear
Works with: SMTP
Notable features: Multithreaded SMTP mail handler. Supports Eudora and Netscape Mail. Supports e-mail scanning in Microsoft Word, Microsoft Excel, PowerPoint, text, and Adobe PDF.

Tumbleweed Secure Mail (MMS)
Works with: SMTP
Notable features: Filters messages based on end-user or domain address, or other criteria. Scans content of inbound and outbound messages. Strips portions of outbound message header.

Services
The following services block spam before it reaches your mail servers.

BrightMail Anti-Spam
Notable features: Samples spam sent to over 100 million e-mail addresses. Staff push spam-blocking rules to dedicated servers at your site. Web-based interface. Anti-virus available.

eDoxs XP4
Notable features: Uses BrightMail engine to filter mail based on content rules and provide anti-virus protect via Symantec's Anti Virus Research Center.

Habeas
Notable features: Uses licensed set of headers to guarantee that sent e-mail is not spam.

MessageLabs SkyScan AS
Notable features: Spam can be blocked or sent to a system administrator. Via the Web-based management interface you can select which IP addresses, domain names, and specific e-mail addresses to block. Uses a combination of public and internal company white and blacklists.

Postini Junk Email Assistant
Notable features: SMTP statistics. Systemwide alerts. Real-time heuristic content analysis. Centralized management of applications. No hardware or software installed at your site.

Singlefin Email Gateway Services
Notable features: Automatic filtering to separate inbox. Web-based control panel. Message backup. Virus protection via Sophos and Trend Micro. No hardware or software required at your site.

Syntegra eMail Sentinel
Notable features: Works with any SMTP messaging server. Sendmail-based SMTP router. Centralized server-based tools that protect against Internet spam attacks. Web administration tools. Statistical analysis filtering process.

Unitedmessaging messagecontrol
Notable features: Automatic filters for Reverse DNS, MAPS RBS, MAPS DUL, and MAPS RSS. Rules applied to outbound and inbound messaging.

Hardware
Hardware-based e-mail screening gateways can handle a higher volume of e-mails than their software brethren. These appliances sit between your router and mail servers (or can replace your mail servers).

Ciphertrust IronMail
Notable features: Distributed signature networks. Weighted keyword filtering and header analysis. Heuristics-based inspection. Reverse DNS lookup and local deny lists.

Escom ASMTP Appliance
Notable features: Company's ASMTP technology runs as a proxy server daemon on Linux. Handles both SMTP and Extended SMTP messages.

IronPort A50
Notable features: Delivers over 500,000 messages per hour. Monitors top domains by recipients in queue. Multiple alert events. Logs mail, system, NTP and FTP events.

McAfee WebShield e500
Notable features: Scans SMTP, HTTP, FTP, and POP3. SSL Web-based console for remote management. Content and attachment filtering. Supports DNS-based black hole lists.

Mirapoint MD300 Internet Message Director
Notable features: Outbound message content filtered to enforce corporate policies. Can be managed via HTTPS Web interface, command line interface (CLI), or Java GUI. Integrates with LDAP servers.

Vircom VOP modusMail Enterprise
Notable features: High capacity secure messaging server. Sieve-based anti-spam filter. Anti-virus scan engine.