BitDefender Mail Protection is a powerful mail filtering solution that provides antivirus and antispam capabilities to Linux mail servers. Both sent and received messages are scanned in real-time, avoiding possible infections and preventing anyone from sending an infected message. It claims a 100% detection rate for all viruses in the wild through its powerful scanning engines, which are certified by prestigious testing labs.
Mailonator is a system that guarantees the delivery of email attachments quickly and securely and avoiding any restrictions that might be in effect for the email recipient. Mailonator software installs on a server, so the email service and client tools never need to change. It works by intercepting email messages, stripping the attachments, and storing them on a server. In addition, Mailonator sends you an email notification when recipients download your attachment, and provides system administrators with usage statistics.
eximstate is a server/client project for monitoring a number of Exim installations. The clients are installed on each of the mailservers running exim and the server runs on the monitoring server. Each client reads the queue on the mail server and sends the total number of messages, the number of frozen message, and the number of bounce messages to the server. The server stores this data and uses RRDtool to make a graphical representations of the data.
hermes is a generic, transparent and multi-platform anti-spam SMTP proxy that uses a combination of techniques (like greylisting, throttling, DNS white/blacklisting, SPF, etc.) to stop spam from reaching your mailbox. Many mailboxes see a 98% spam reduction with no false positives, as hermes is not filtering email based on content, but on strict adherence to the SMTP standards. It's also compatible with most SMTP extensions like STARTTLS (for SSL security) and SMTP-AUTH (for user authentication).
DynamicRelay prevents your customers from sending spam, and authenticates users using POP or IMAP to send email in a pop-before-smtp fashion. You can use it with the wu-imap, dovecot, Courier, and Qpopper IMAP/POP servers, and with Postfix or Sendmail. You set the limit to the number of email messages a user can send per day. This is useful when you have users infected by viruses that send thousands and thousands of spam messages, or who send spam deliberately. You can also control how long users are allowed to send email after their last POP or IMAP authentication. Abuses are logged and emailed to you, and you can put your own static entries in the access file.