Proto Balance Mail is an enterprise SMTP cluster solution that supports distribution of email accounts. It scales up to 1,000,000 mailboxes apportioned over up to 125 backend mail servers (8000 mailboxes per server). No NFS or SAN is required. SOA is configurable with SOAP/XML. Anti-spam settings can be set per-user. Grey-listing is supported. Mal-ware is automatically detected and infected client PCs are automatically black-listed. POP load balancing is done. SMTP AUTH is supported. There is a Web-based management interface. Spam blocking is done by on-the-fly connection behavior analysis. It handles up to 10,000 concurrent SMTP connections. Streamlined CRM integration is done with HTTP+XML posts. Email-alias lists, forwarding, and out-of-office auto-reply are supported.