maildir-bulletin takes a message on standard input, i.e. it runs in the same fashion as a mailing list program, and puts the message in every user's Maildir. The message is created once and links are created from all user's Maildir's to the original. This saves greatly on disk space usage and time. Delivering a 1K message to 100,000 users should only take a few hundred K of disk space and take ten or twenty minutes. If you have an alias to expand to 100,000 users the same 1K message will take 100M of storage and take several hours.
AXIGEN is a fast, reliable and secure mail server with an open architecture. It is designed for easy management and allows full control of the email traffic from a central Web/CLI admin module. AXIGEN provides ESMTP, IMAP, and POP3 services and has been tested with standard mail clients. A special Webmail module enables email access and delivery from Web browsers. During the evaluation period, users are provided with full technical support.