With an exclusive domain and one mailbox from ISP, you can add or remove mailboxes at any time. That means you don't need to pay any extra money to your ISP for the mailboxes you add, perfect solution for small business. Requirements for ShareMailPro: Your company must has a Domain. Must apply 1 mailbox under this domain from your ISP, and the ISP must foward all the messages to this domain to this mailbox . Features: Auto recv and send mail AntiVirus AntiSpam MX delivery support Support alias mailbox Email broadcasting Support DUN NT Service POP3 Proxy Refuse email spam Log Email backup Firewall/Proxy support Remote control Inner mail exchange Maillist support Priority support SharemailPro can support more than 100 mailboxes. The Free version only supports 5 mailboxes . For more mailboxes, register the software .