SPAM filter

Our spam scanner filters all incoming mails and adds a flag to the header. If the spam filter is activated, it has the following effects:

  • Mails classified as spam end up in a separate folder called "Spam", which you can see or control via webmail or IMAP. You can empty this folder completely with one click. All e-mails that end up in this folder are automatically deleted after 30 days.
  • If you have entered a forwarding to another address, then no mails classified as spam will be forwarded to you. So, if you miss an email or want to check regularly for false positives, you have to use our webmail or switch off the spam filter and filter out the spam yourself, e.g. with your mail client.

Configuration of the spam filter

You can enable or disable your spam filter in the settings of our Webmail-Systems SOGo. After logging in, open the settings by clicking on the cogwheel symbol next to your name.

  1. Switch to the submenu E-Mail
  2. Select "Filter" in the navigation bar of the main window.
  3. Make the desired settings
  4. Do not forget to save your changes!

More information about fighting spam

SPAM - what is that?

Spam is a nuisance. Spam is unsolicited e-mail messages sent to the user without being asked, sent in bulk and containing advertising or harmful content. Almost every Internet user will have had the advertising for the famous blue pills in their mailbox at some time. Over 98% of messages on the Internet are identified as spam.

Of course, the mail system of the University of Konstanz is also affected by this; we too receive several hundred thousand spam messages per day. In order to protect you as a user from this as much as possible, we have various techniques in place to combat spam.

SPAM - what KIM does against it

The fight against spam roughly takes place in three steps. Let's look at the different stages of fighting spam in more detail.

1. SenderBase Reputation Score Classification

Our two Ironport(tm) devices as mail acceptance servers first check for each incoming connection whether the IP address of the submitter has a bad rating. This rating data is stored in the Ironport database  SenderBase. The Ironport machines update their local copy of the rating database every five minutes. If a computer sends out masses of unwanted advertising messages (through a Trojan infection, botnets or commercial mass spammers), the rating of the IP address of this computer deteriorates very quickly - with the consequence that all mail systems that rely on SenderBase no longer accept connections from this computer. SenderBase receives feedback from very large mail operators so that this list is very representative.

2. virus and spam check

If the sender was allowed to deliver the message to us (SenderBase rating OK), the mail will now be checked for viruses by a Sophos virus scanner and examined for spam characteristics by Ironport Antispam. This spam filter uses special word/hash/pattern files that characterize spam. These tables are checked every five minutes against Ironport's databases, which contain the instantaneous patterns of all spam occurring around the world. These pattern files are also kept up-to-date by feedback from the (very) large mail providers.

If a message is classified as spam by the Ironports, it is marked with an entry in the header line: "X-Spam-Flag:Yes". This entry can then be used in various mail clients for automatic filtering.

Please note: In rare individual cases, so-called false positives can occur, where a "good" mail is inadvertently classified as spam. However, these cases are in the per mille range.