Trilent Mail Proxy   
http://www.trilent.net

This firewall-friendly mail (SMTP/POP3) proxy enables small network users to access and distribute email via a single Internet connection, eliminating the need for dedicated mail servers. This is an application-level proxy. It enhances network security by enforcing mail protocol rules and offering many security promoting features, such as access control and event logging. Once configured, the proxy works unobtrusively in the background and requires minimal attention. It offers "install-and-forget" operation. The proxy is designed with reliability in mind. Its modular, multi-threaded design and implementation as a Windows service contributes to its superior stability (it carries the "Designed for Windows" logo.) The proxy supports up to 30 concurrent mail connections, offers extensive compliance with Internet standards and includes a simple mail monitor, capable of monitoring mail connections. Note: To run the program you need a free trial registration key from publisher's Website.

Mail Trustee   
http://ml-tr.com

Do you get a lot of unwanted mail in your mailbox? - Are you tired of selecting unwanted messages and wasting time on them? - Do you lose wanted messages amidst all that trash you get in your mailbox? - Do you pay extra money because your mail client receives unsolicited mail? Mail Trustee will help you solve these problems and more! Mail Trustee: a system of E-mail protection programs intended to protect your mailboxes from unsolicited mail (spam). Mail Trustee acts as a proxy server, which is situated between your mail client and mail server. Our unique technology will filter out a huge percentage of the spam, allowing minimum possible mail server access time with a minimum volume of sent and received information. Mail Trustee supports up to 255 mailboxes and each mailbox may have its individual settings for spam filtering and mail rocessing. Mail Trustee has a flexible system of settings which allows adapting it to a user's needs. An individual functioning cycle can be set up for each mailbox; it will include: - Receiving mail from mail client with further transfer to mail server - Transfer of received mail from mail server to mail client - Establishing an Internet connection if needed - Mail transfer to mail server - Mail analysis on mail server, unsolicited mail detection for decision-making (delete, accept, etc.) - Receiving mail from mail server - Interrupting an Internet connection if needed While analyzing mail, all necessary types of checks are performed, which gives an excellent result in spam filtering. The following checks may be used in the system: - Allowed E-mails - Forbidden E-mails - Allowed zones - Forbidden zones - Allowed domains - Forbidden domains - Field validity "To:" - Field validity "Received:" - Field syntax "From:" - Lists DNSBL - Allowed expressions in Subject - Forbidden expressions in Subject - Forbidden expressions in Header - Allowed expressions in Message - Forbidden expressions in Message