Kerio offers a mail server with anti-virus, anti-spam, and content filtering. As a mail server, it is a cost-effective alternative to other products and offers extra features. For example, it can be used with a dial-up internet connection because it supports POP3 as well as SMTP for mail collection from an ISP. It has Extended Turn (ETRN) support for dial-up to extend SMTP if required. Client machines can be supported via POP3, IMAP, or a webmail interface.
Anti-virus for incoming and outgoing messages is offered with the Kerio MailServer with McAfee Anti-Virus integrated or with your own copy of anti-virus software from select third-party suppliers.
SpamAssassin, a third-party anti-spam product, is standard in Kerio MailServer and uses a heuristic approach to rate received messages with a probability of being spam. It can also use a public realtime blackhole list (RBL), and verification of a sender's domain name. It can check against a list of IP addresses that ISPs have allocated to dial-up users, on the assumption that dial-up users don't send email other than via their ISP's mail server.
Other restrictions aimed at controlling spam and defeating denial-of-service (DoS) attacks can be implemented. For example, you can limit the maximum number of messages that can be sent per hour from a single IP address. You can limit the maximum number of concurrent SMTP connections and prevent the Kerio MailServer being used as an open relay by spammers.
Content filtering includes the blocking of attachments by filename or file type, but is basic other than its anti-spam functionality. You can perform lexical searches for selected words of your own choice within the subject, but not within body text or attachments.
Other features are automatic backup of emails to a remote server and the SSL encryption of all communications between clients and the mail server. Kerio MailServer runs on Windows 98/Me/NT/2000/XP, Linux, and Mac OS X.