NoSpamToday! for Servers - System Architecture

Filter Chain Architecture

NoSpamToday! submits incoming mail to a series of mail filters, the so-called filter chain. Examples of mail filters are the built-in attachment blocker, third-party virus checkers, or SpamAssassin.

Each filter analyzes the message and returns a filter result telling NoSpamToday! what to do with it. Example filter results are: accept and deliver, or reject and delete. The overall filtering result is always the ”worst” result, for example if the virus checker returns ’reject and delete’, it will override another filter returning ’accept and deliver’.

The location of a filter in the filter chain matters: To help conserve resources and to increase throughput, filters lower down in the filter chain are not invoked if an earlier filter has already decided that a mail should be deleted.

Transparent Proxy Technology

The NoSpamToday! proxy accepts incoming SMTP or POP3 connections and forwards all requests to your existing mail server while scanning incoming mail for SPAM or viruses. This has several benefits:

• Most of your mail server's settings remain in effect. If you choose not to accept mails to certain recipient addresses, NoSpamToday! won't accept it either. If you use SMTP AUTH, you can still use it after NoSpamToday! has been installed.
• NoSpamToday! for Servers automatically supports the same SMTP or POP3 extensions as your mail server.
• If your mail server is up and running, there is little to change in its configuration to make it work with NoSpamToday!.
• NoSpamToday! does not implement the overhead of spooling mails until they can be delivered to your mail server. It is therefore comparatively simple and straightforward to use.

NoSpamToday! never accepts mails on its own volition, it always makes sure a mail has been accepted by your mail server before acknowledging a successful mail transmission.

Full Multi-Domain Support

Usually, NoSpamToday! is a proxy only for a single mail server. ISPs usually have more than one mail server and may want to filter mail for all these servers and domains. NoSpamToday! allows to configure an unlimited number of SMTP or POP3 proxy ports, each with its own incoming and outgoing server settings and each with its own filter chain. An ISP can use this to configure each proxy separately and adapt it to the needs of each of his clients.

Learn More ...

• Read more about NoSpamToday!'s Network Configuration options.
• Read more about NoSpamToday!'s Core Features and Benefits.