Spam Defenses

Unsolicited commercial email (better known as spam) has become a tremendous problem for every email user on the internet. Here at Greenwood District 50 a large portion of our incoming mail every day is spam. However, we have put in place some state-of-the-art spam defenses that you can utilize to keep your mailbox clean. Of course, the spammers change their tactics regularly, so the information provided here may change as well.

Automated Defenses

For every user, we have some “automated defenses” that cut down on the amount of spam that gets into our system. We use a mix of DNS blacklists, SMTP rules checks, and sender verification to stop many messages before they are even accepted by our servers. Then, any mail that passes those barriers is run through a filtering system that scores it for its “spamminess.” If a message’s score is too high, it is blocked.

Of course, there is always the possibility of a “good” email being blocked by our system, so our automated rules are fairly conservative: they almost never block “good” emails, but they also let more spam through than you might like.

Opt-In Defenses

If our automated defenses are not blocking enough spam for you, then it is time to look at enabling one or both of our optional defenses. These are much more aggressive than the defenses in place for all users, but they require some understanding and attention to make them work their best and to eliminate “good” email being blocked by mistake.

Greylisting

This defense takes advantage of the fact that spammers often do not use “real” mail servers to send their messages. It works like this: when someone who has never sent you an email before tries to send you a message, our server tells theirs to “try again later.” Real email servers will try again in a few minutes, at which point our server lets the mail go through. Spammers usually only try once, so the first rejection is “final” for them.

When you use greylisting, you should know that the first email you receive from a particular address may be delayed for some period of time (usually less than 15 minutes, but the time is actually up to the sender’s server.) After that first email, though, messages from that person will come through instantly. Occasionally, mailing lists will have problems with greylisting, so if you enable it and have problems getting messages from lists, let OCS know and we can make an exception.

To enable greylisting for your account, simply send an email to “greylist” in GroupWise with the subject of “enable” (without the quotes.) After a few minutes, you will receive a response telling you that greylisting has been enabled for your account.

To disable greylisting for your account, send an email to “greylist” with the subject of “disable.” Again, you will receive a confirmation email letting you know that your address will no longer have greylisting applied to it.

Maia Mailguard

Maia Mailguard lets you manage your personal anti-spam settings separately from every other user. It also allows you to help “train” our scoring system by confirming which messages are spam and non-spam. Using Maia Mailguard in combination with greylisting will make an enormous difference in the amount of spam you receive.

Maia keeps a copy of all of your messages, both spam and non-spam. Maia will send you a “digest” email of messages that it has seen so you can catch any “good” emails that it might have mistakenly marked as bad. If you choose to use Maia Mailguard, you should try to log into it at least a few times a week to confirm “good” and “bad” emails. If you don’t have the time to rate your messages, then you should make sure to delete them from Maia.

Maia is easy to use, but setting it up for your account involves your taking  several steps. For a walkthrough (with screenshots) of enabling Maia for yourself, click here.