Cyrus is a scalable mail server available for both personal and professional use. Cyrus is based on many standards and offers two downloadable editions. As for Cyrus IMAPd, it is an open source IMAP server. The project came from Carnegie Mellon University in the US and dates back to 1994.
It supports advanced functionalities such as push (IDLE), ACLs, shared folders, quotas, server side filtering (sieves) and a large number of SASL authentication methods.
Cyrus IMAPd is distributed under the BSD License.
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