Email Features Spam Prevention

The email services at have some special features that may help you in your fight against spam. The built-in spam filter/identifier is usually quite successful in identifying spam, but with your cooperation you can make it even better at doing its job. The way the spam filter works is by determining a "score" for each email. The higher the score, the more likely the email is to be spam, the lower the score, the less likely.

The Standard Spam Filter

As you may know, or may have noticed, by default, you have a folder titled Spam inside your INBOX. If you haven't noticed, that's probably because you aren't viewing the folders that are inside your INBOX. The details of how to do this depend on the mail client, but in short, there's usually some sort of mark next to the INBOX folder in your list of folders (on Windows this is frequently a plus sign in a box (example), on Macintosh this is usually a gray triangle (example)). Click on this symbol to see the folders within that folder.

Mail, by default, is delivered with some filtering already applied. Messages with very high scores (and thus almost certainly spam) are delivered to your Trash folder (and the learning folder), and messages with middling scores (probably spam, but possibly not) are delivered to your Spam folder. The messages in the Trash you probably don't need to check over for mistakes, while the messages in the Spam folder may not actually be spam.

The Advanced Features: Learning From Mistakes

The spam filter is not always perfect. Sometimes messages that are spam do not get marked as spam. Sometimes messages that are not spam get marked as if they were spam. Fortunately, both of these problems can be corrected, and can be used to improve the accuracy of the filter for the future.

Spam That Got Through

When spam gets through to your INBOX, this is generally because it did not "look" like spam to the filter. The way to improve the accuracy of the spam filter is to teach it what spam looks like by providing it with examples. The way to provide it with examples that it can learn from is to put spam (especially spam that was not correctly recognized as spam) into a "magic" folder specifically for that purpose.

Inside your Spam folder, there is a folder titled Report (if it is not there, you can create it). Any email you move into this folder will be treated as new learning material for the filter; it will examine every message in the mailbox to learn to identify it as spam in the future. The filter will also report the spam message to the proper authorities, so that other people can stop receiving that particular spam as well. Doing this makes the filter more accurate in identifying spam. Once a message has been learned as spam, it will be deleted.

What makes this folder "magic" is it's name and location; the spam filter looks for messages to learn from inside any folder with the name Report inside the Spam folder (capitalization is important).

Innocent Mail Incorrectly Marked as Spam

Sometimes, when reviewing the mail you have received in your Spam folder, you may discover a message that is not actually spam and has been incorrectly marked as spam. It may even be hard to read because of the sanitization process that is applied to messages identified as spam. This can be reversed!

Similar to the Report folder, inside your Spam folder there is another folder titled NotSpam (if it is not there, you can create it—note that there is no space in the name, and capitalization is important). Any messages you move into this folder will be examined and learned as innocent, so that in the future, similar messages will not be considered spam. Once a message has been learned as not being spam, it will be re-delivered to your INBOX, as if it had been correctly identified in the first place.

Virus Protection

If you are worried about email viruses, you are right to be worried. As we all know, email is one of the most popular methods for distributing such malicious software. Email that goes through the email server is thoroughly scanned for viruses using one of the best scanners in the business, ClamAV, with a database of recognized viruses that gets updated several times a day. That said, no virus scanner is perfect. Sometimes virus writers figure out sneaky ways to attack the scanner itself, and brand new viruses aren't recognized until the next database update. So, while there is a solid layer of protection around the email at, you should practice due diligence with your email.

Server-side Filters

Sometimes, you may decide that you want to do some filtering of your email before it is delivered. For example, you may wish for all mail from a given email address to be prevented from being delivered to your Spam folder. Or you may want to never receive mail from a given address entirely. Both of these things may be accomplished with what is called "server-side filters". These "filters" or "rules for delivery" are in many ways similar to the sort of filtering that many email clients can do, with the exception that these rules are on the server itself as part of the delivery mechanism, and can therefore override the standard filtering of spam into the Spam and Trash folders.

Setting up these filters can be done from the web page, which is linked from the main webpage. You need your email address and password to edit them (this prevents just anyone from editing your filters). Once you've gotten to that webpage, using the filters should be relatively straightforward: rules are evaluated for delivery in order from first to last, and any mail that is not handled by one of those rules will be delivered as normal (in other words, to your INBOX unless it is considered spam).