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.