Mailserver Advice Required

Need advice (and some support in setting up) a e-mail server. Prefer Linux/Open Source. Must support IMAP, LDAP, Outlook 2003 onwards, Iphone (IMAP) Would be good if did (in order): *LDAP authentication *Free/Busy Time *Rules if attachments >3MB *Archive incomming / outgoing email *Web Interface *Spam filter *Virus filter Any suggestions? ## Deliverables 1) All deliverables will be considered "work made for hire" under U.S. Copyright law. Employer will receive exclusive and complete copyrights to all work purchased. (No 3rd party components unless all copyright ramifications are explained AND AGREED TO by the employer on the site per the worker's Worker Legal Agreement). ## Platform Prefer Linux/Open Source. Install on VM Ware