Pop3eye is a POP3 email notifier. It can be placed in a "dock", or use a regular or undecorated popup window. Regular expressions are used to filter email. It can display up to 20 partial lines of the email body in a tooltip window. It can monitor and display an unlimited number of accounts. You can choose to show messages using regular expressions, or delete messages from the server.
PostArmor (formerly MailArmor) helps to keep your electronic mailbox free of spam: it looks at the relevant parts of your email before it leaves the mail server, and lets the legitimate messages pass through undisturbed, while leaving suspect messages on the server to be reexamined later or just deleted after a while. It works as a POP3 email proxy, with support for POP, APOP, and IMAP servers. It supports SpamCop reports and blacklist, and the ORDB and OSIRUSOFT blacklists.
Proto Balance Mail is an enterprise SMTP cluster solution that supports distribution of email accounts. It scales up to 1,000,000 mailboxes apportioned over up to 125 backend mail servers (8000 mailboxes per server). No NFS or SAN is required. SOA is configurable with SOAP/XML. Anti-spam settings can be set per-user. Grey-listing is supported. Mal-ware is automatically detected and infected client PCs are automatically black-listed. POP load balancing is done. SMTP AUTH is supported. There is a Web-based management interface. Spam blocking is done by on-the-fly connection behavior analysis. It handles up to 10,000 concurrent SMTP connections. Streamlined CRM integration is done with HTTP+XML posts. Email-alias lists, forwarding, and out-of-office auto-reply are supported.
The QmailToaster is an RPM-based Qmail distribution for CentOS, Fedora, SuSE, and Mandriva. This system is designed for ease of deployment and includes strong anti-spam systems. This includes support for SRS, SPF, DomainKeys, and virtual hosting on the SMTP side. On the user side, this has a Web-based administration interface and supports POP3, POP3 over SSL, IMAP, and IMAP over SSL.