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Sorting spam using SUNET's email filter

SUNET's email filter is a service that classifies email automatically to determine whether it is spam or not. This is done by looking for a vast number of properties that may indicate whether a message is spam or not. Each property is worth a certain number of points, and when a message receive over approximately 5 points, it is classified as spam. If a message receives over 10 points it is rejected entirely.

Although SUNET's email filter works well, it will occasionally mis-classify email. Sometimes spam is not detected, and on rare occasions legitimate email is classified as spam. You can report such incidents to IRT.

Read more about reporting spam

Central spam sorting

If your email account is on the central email server and you use IMAP or Outlook (not POP) to read mail, then the email system automatically places spam in a separate junk email folder instead of your normal inbox. Check your junk email folder regularly to ensure that no legitimate email has been classified as spam and to report all your spam to spam@liu.se (even if it has been correctly classified, reporting it may improve the service further).

Employees

Employees with their email account in Exchange who use Outlook to read email have automatic spam sorting. Messages marked as spam will be placed in the junk email folder.

Students

Sudent email is handled by Google, so Google's spam filtering is employed. Check Google's documentation for more information. When reading mail through IMAP, the email software may need to be configured to place spam in a separate folder; see the instructions below.

Information from SUNET's email filter

This is an example of the beginning of a typical spam email:

From: igced brown <vhuser52@fuse.net>
Subject: Good Vibrations !!! bvy
To: v.a.kant@liu.se
Date: Thu, 1 Mar 2012 19:21:03 -0400

<HTML><BODY BGCOLOR="#000000"></P><P ALIGN=CENTER>
<FONT COLOR="#ffff00" BACK="#000000" SIZE=3 PTSIZE=10
FAMILY="SANSSERIF" FACE="Arial" LANG="0">
Sylvester won't eat your Tweety Bird ?

SUNET's email filter adds several headers to the message stating that the message is spam and what the grounds for classification are:

x-spam-flag: YES x-spam-score: 9.50 (*********) [Tag at 5.10] FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,FREEMAIL_REPLYTO,SUBJ_ALL_CAPS, T_FREEMAIL_DOC_PDF,T_TO_NO_BRKTS_FREEMAIL,Bayes(0.9994:5.0)

The key header is "X-Spam-Flag: YES". The easiest way to sort spam is to configure the email software to check whether that header is present, and if so, place the message in a junk email folder.

Configuring spam sorting in various programs

This information is only available in Swedish. For assistance, please contact LiU's helpdesk on telephone +46 (0)13 282828 or email to helpdesk@liu.se.

Information in Swedish

Send email to LiU's helpdesk

 


Page manager: karin.linhardt@liu.se
Last updated: 2012-09-06