The Apache James Server is a 100% pure Java enterprise mail server based on open protocols. Currently supported are SMTP, POP3, IMAP (Mail) and NNTP (News) protocols together with several different storage solutions.
The James server also serves as a mail application platform. The James project hosts the Apache Mailet API, and the James server is a Mailet container. This feature makes it easy to design, write, and deploy custom applications for mail processing. This modularity and ease of customization is one of James' strengths, and can allow administrators to produce powerful applications surprisingly easily.