What is Spam ?
Spam is the common term for Unsolicited Commercial Email (UCE), the Internet version of junk mail. Unlike postal junk mail where the sender has to pay for printing cost and stamps for each delivery, Spammers can send millions of emails per day on a cable or DSL line at virtually no cost. The only cost is your time to receive and read those spams.
Why are there Spams ?
The shortcoming of the current Internet e-mail architecture is that there is no good and commonly available mechanism to check against the identity of e-mail senders, meaning that spammers can forge to be anyone to send e-mail to any other.
How does Netfront filter Spams ?
We have employed a very effective and fast method to filter spam, at the speed of 2-5 seconds to filter each e-mail.
First stage: the e-mail servers calculate a digital signature of any e-mails received, and use that signature to check the number of copies of the same message other ISPs have received. If that number is exceedingly large (over a million) and the e-mail is not in our white-list, the e-mail is discarded immediately. This is the Default Filter, which filters 95% of spams with no loss of legitimate e-mails.
Second stage: the e-mail server tries to guess how likely a piece of e-mail being spam and associate it with a numeric score. The score is added to the header of the e-mail. If you have tightened your filter to levels Tightened, Intermediate, or Aggressive, then the filter will check that score and move likely spam e-mails to a "spam" folder. E-mails that pass through the filter will be delivered to your normal inbox. The "spam" folder can be accessed via our webmail site http://webmail.netfront.net
How do I tighten my spam filter ?
The filter has three levels of aggressiveness (Tightened, Intermediate and Aggressive). The more aggressive the filter, the more spams removed but the chance of incorrectly picking legitimate e-mails as spam slightly increases too. So you are suggested to visit the "spam" mailbox periodically to check if good e-mails are filtered and adjust your filter level accordingly. Also, the "spam" folder will be counted as server disk space used by your account, so please clean it when necessary.
Are there other ways to use the filter ?
Yes. If your e-mail client software can filter e-mail based on its headers, (e.g. Microsoft Outlook), you can configure your e-mail client to do the filtering. The score is represented by a header line "X-Spam-Level:". More "*" means the email is more likely a spam. Normal email should have "*"s less then 8.
To use this filtering method, you have to set the spam filter to Default Filter on our servers. This will make the filter at stage 2 to only guess the spam likeliness, add it to the header, but not move anything to the "spam" folder. You can then use your e-mail client software to take desired actions based on the header lines.
Is my privacy protected ?
Yes, because no other people inspect the content of your e-mail, and the e-mail servers only calculate and inspect digital digests of e-mails but do not look into the context of those e-mails.
Does the filter delay my e-mails ?
The e-mail filtering action will add 2-5 seconds delay to each e-mail.
How effective is this filter?
The figures below are for reference only. It might not apply to your specific situations.
Is this service free?
This service is free for now. We will provide prior information if any charges shall be required.