One of the challenges I often get asked about is "how can I use the Intellegent Message Filter on SBS 2003 if I am using the POP connector?"
The answer is that there are many POP connectors / pullers that essentially pull down the email from a POP account and then simply pass the mail to the Exchange server via SMTP. Here is a brief list which includes ones I have used in the past and others I have not. This list has been primarily taken from an article found on slipstick - a great resource!.. To see the full article click here. If you have any other suggestions, please let us all know!
ARX POP3 Connector
Supports filtering rules and DNS verification on incoming messages to reduce spam.
EFS (Email Forwarding Server)
EFS is a FREE POP3 gateway for any SMTP server such as Microsoft Exchange. It pulls mail from a Pop3 mailbox at your ISP and distributes the messages to users on a local SMTP mail server. EFS requires you to have a registered Internet domain name (to accept and forward mail for).
EMP (Extensible Messaging Platform)
Antispam security software that includes a POP3 connector. Works with Exchange 2000, as well as earlier versions.
Exchange Connector allows you to integrate your existing POP3 mailboxes with Microsoft Exchange Server 2000 or 2003 by downloading mail from POP3 mailboxes and delivering the messages to your Exchange Server accounts. Exchange connector runs in the background as a Windows Service and can be configured to download only during specified hours, such as between 9AM-5PM Monday-Friday and includes a "Download Mail Now" button for immediate downloads. It provides support for APOP (enhanced POP3 security), archiving, and SQL Server logging.
An email gateway (connector) that retrieves messages from Internet POP3 email accounts (IMAP also supported) and delivers them to Exchange Server mailboxes. Supports single and multiple user POP3 accounts, unlimited POP3 accounts, unlimited ISPs and SMTP authentication when sending to Internet.
IGetMail acts as a POP3 gateway to automatically download your incoming POP3 mail from multiple remote servers to a single, local Microsoft Exchange Server. Downloads and copies e-mail from multiple individual e-mail accounts and multiple domains, using a single connection to fetch all your e-mail.
Inox pop3 connector
Runs as an operating system service and can both receive POP3 and send messages. Supports multiple servers and multiple accounts.
Mail Essentials for Exchange
Offers many mail filtering features in addition to the POP3 connector. Exchange 2000 and Small Business versions available.
Native POP3 Connector
Native POP3 Connector installs as a connector to Exchange and is configured using Exchange System Manager. It supports a large number of mailboxes (each one may be catchall accounts), multi-threading processing, flexible scheduling of POP3-mailbox querying, and integrates with the Active Directory
Supports mail forwarding without attachments (i.e. for SMS messages), dial up (RAS) connections and checks all inbound mails with a standard virus checker i.e. Norton Antivirus. Works with every version of Exchange Server including Small Business Server, 2000 and 2003, dial-up, dial-up routers, ADSL and leased-line connections to the Internet.
Supports every version of Exchange server including Small Business Server and Exchange 2000/2003, any ISP's POP3 or IMAP server, even the older ones, that do not support the Received for: header line. Works with dial-up, dial-up routers, ADSL and leased-line connections to the Internet.
Pro version also available which includes all features found in the standard version plus a self-updating RAV virus scanner, antispam filtering, and rule-based message distribution.
A command line utility to add POP3 mail collection to most SMTP mail servers. Easy to configure with multiple POP accounts to collect from, once started the POPWeasel collects mail from each account, reads the mail headers and routes the mail to your mail server for distribution to your users.
POP3 connector including spam filtering with SpamAssassin, interface for virus scanners, content-checking, outgoing mail handling and more.
SmartPOP2Exchange works in the background and downloads all messages from various POP3 accounts and forwards them to your SMTP/Exchange server. The configuration tool allows you to adjust common options, like download interval, timeout, log file etc. and to add, delete or configure your SMTP/Exchange and POP3 accounts. An included spam filter allows to tag or to delete mails that have been identified as spam by SpamAssassin. SmartPOP2Exchange also supports rules which allow you to define additional actions for certain messages.
Credit for the links etc to Slipstick: http://www.slipstick.com/exs/popconnect.htm