Haraka Description
Haraka can handle thousands of connections simultaneously and deliver thousands messages per second. Haraka and its plugins are both written in asynchronous JS, and are therefore very fast. Haraka is a very good filtering MTA and has excellent spam protection (see the plugins). It also works as an MSA on port 587, with auth and Dkim_sign enabled. Haraka does not claim to be an IMAP or LDA server (like Dovecot, courier or Dovecot), or a mail store like an exchange (or postfix/exim/qmail). Haraka is commonly used with these systems. Haraka comes with a built-in scalable outbound delivery engine. Mail marked for relaying (e.g. via an auth plugin), is automatically queued up for outbound delivery. Haraka's plugin-based architecture allows for an easily extensible MTA to complement traditional MTAs, which excel at managing mailboxes but lack sufficient filtering.