In build 3212 we have introduced a SOCKS4 and SOCKS5 proxy service along with the ability for the Outgoing SMTP Client to use a remote SOCKS proxy. Again, this is specific to the Advanced Router.
Sending mail directly even when your ISP prohibits it
The SOCKS proxy in the SMTP client can be an essential tool in sending outgoing e-mail directly (and with the benefits that direct MX resolution provide) when your ISP prohibits outgoing port 25 connections. Many ISPs charge an additional fee to provide an unlimited account and it is usually much cheaper to arrange an external SOCKS proxy to use.
In an alternative scenario, your organisation may be widely distributed with some servers behind ISPs that impose limits and some that are more flexible. In such a case you can use multiple Mailtraq servers to divide the workload or to maintain organisational structure. Mailtraq servers that are on machines with unblocked Internet access can act as proxies for other Mailtraq machines.
Providing a SOCKS Service
Some Internet applications only provide support for the SOCKS proxy as because of its simple design, built in security and the ability to specify a remote machine.