Mail Storage Guard is an extension for Microsoft Exchange 2000/5.5 and IIS SMTP servers, designed to protect your mail server from spam, prevents mail relaying, mail bomb and NDR attacks. The protection is realized both on the level of SMTP protocol and on the level of message delivery to storage.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 mail server administrator or set to Bad mail folder.Features:1. Protection on SMTP protocol level lets us to block messages, getting only head of message. Such protection method reduces incoming internet traffic and absolutely excludes the harmful program coming to your server.2. Protection on transport level lets to manipulate the message coming to your server, but not yet arriving to the receiver mail box. Such protection method lets to block the message but at the same time send it to mail server administrator for analysis.3. Message delivering only to registered receivers. Microsoft Exchange gets all incoming messages by SMTP protocol. If server can\'t find message recipient inside the system then the message is returned to the sender (non-delivery report, NDR). This scheme has serious hole in safety as sender address isn\'t checked and the violator can specify any address as replay address. Mail Storage Guard may reject all"misaddressed"mail or point such messages to specified mailbox.4. Message blocking with the help of 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 to block whole groups and even whole domains.5. Message blocking with the help of public DNS blackhole list (ORDB, SPAMCOP, SPAMHAUS, DSBL and others).