Mail Storage Guard is an extension for Microsoft Exchange Server 2000/2003, Small Business Server 2000/2003 and IIS SMTP servers, designed to protect your mail server from spam, prevents mail relaying, mail bomb and NDR attacks. The protection is realised both at SMTP protocol and message delivery to storage levels. Mail Storage Guard follows all incoming mail which comes to your SMTP server and if the message is spam then it is deleted, rejected, sent to your mail server administrator or sent to a Bad mail folder. Features: 1. Protection at SMTP protocol level lets you block messages, getting only the heads of messages. Such a protection method reduces incoming internet traffic and completely excludes harmful programs coming to your server. 2. Protection at a transport level lets you manipulate the message coming to your server, but not yet arriving to the receivers mail box. Such a protection method lets you block the message but at the same time send it to your mail server administrator for analysis. 3. Message delivering only to registered receivers. Microsoft Exchange gets all incoming messages by SMTP protocol. If your server can't find the message recipient inside the system then the message is returned to the sender (non-delivery report, NDR). This scheme has a serious hole in safety as the sender's address isn't checked and the violator can specify any address as the reply address. Mail Storage Guard can reject all "misaddressed" mail or point such messages to a specified mailbox. 4. Message blocking with the help of a Senders Black-List. You can create your own senders black-list and insert there the addresses of spammers. To the senders black-list you can insert e-mail addresses, as well as e-mail addresses with masks that lets you block whole groups and even whole domains. 5. Message blocking with the help of public DNS blackhole list (ORDB, SPAMCOP, SPAMHAUS, DSBL and others).