proxy server that offers unrestricted, anonymous access to anyone and everyone. Usually, in the context of spam, this term refers to proxies that allow the user to create arbitrary TCP connections. SOCKS proxies and HTTP proxies with SSL support meet that requirement. Other types of proxies can be "open" too, but they are less useful to spammers.
a computer that has essentially been hacked into and turned into a spam delivery mechanism, usually without the owner's knowledge or consent
a mis-configured proxy server through which an unauthorized user can connect to the Internet
a non-email server that can be tricked into sending email to third parties
a poorly configured web proxy or a compromised computer that will forward HTTP requests from anywhere, to anywhere
a proxy server left open for anyone who can find it to use as their own
a proxy server that allows anyone to connect to it and send requests
a proxy server which will accept client connections from any IP address and make connections to any Internet resource
a proxy service opened to the world for almost any kind of request, allowing anybody to remain anonymous while crawling the net
a proxy that will do this redirection to any destination for anyone without authentication
a server that forwards Internet connections from anywhere to anywhere, no questions asked
A proxy is used to relay traffic from certain hosts to somewhere else, usually from an internal network to the internet. An open proxy is such a proxy that is not properly configured, it will relay traffic from anywhere to anywhere. Thus allowing anyone to access websites, send e-mails or connect to IRC as if they were actually sitting behind your computer. This is of course a bad thing. On IRC for example, abusers can simply connect through a proxy when they're banned, making bans virtually useless.
A proxy server or firewall that lets anybody connect to it. Spammers use open proxies to hide their point of origin. Often combined with open relays.
Software that exists on a server that allows the third-party relay of e-mail messages through ports other than port 25.
An Open Proxy is an email server that allows anyone to construct and send email using that server. Normally an email server will only allow people who have email addresses on that server to send email to other people: open proxies let anyone use the email server to send email.
An open proxy is a proxy server which is accessible by any Internet user.
