You may have noticed an increase in a particular type of email spam, where the spammer uses your email address as the sender in an attempt to lower the spam rating of the message. In order to combat this type of spam, Kerio MailServer available at ZZ Servers includes two special Anti-Spam technologies that use Domain Name services to validate the IP address of a sending mail server.

Here is how it works: When Kerio MailServer receives a connection from a remote mail server, it gathers the sender’s email domain from the email headers. Kerio MailServer then sends a request to its Domain Name Server, asking for a special type of text record (Caller-ID or SPF), which belongs to the sender’s email domain. If this record exists, the Domain Name Server will reply with the contents of the text record, which includes a specially formatted list of IP Addresses that are allowed to send outgoing email using the specified email domain. If the sending mail server’s IP address does not belong to the returned list, the receiving Kerio MailServer will refuse to accept the message. Although this technology is highly effective and yields virtually no false positives, it is rather difficult to configure, primarily because few Domain Name hosting providers support these record types. An extensive Knowledge base article exists in the Kerio website support section that details exactly how to properly configure both Caller-ID and SPF records.

ZZ Servers offers Kerio MailServer as a comprehensive Microsoft Exchange alternative that simplifies administration and lowers total costs of ownership. Kerio MailServer offers cross platform collaboration, mobile wireless synchronization, robust security, automated backups and more. Visit ZZ Servers for a quote today.

Distributed Sender Blackhole List – trusted

Distributed Sender Blackhole List – unconfirmed

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