Information Services

Dealing with spam

You can filter spam out of your INBOX with a spam filter.

To setup a spam filter to deal with spam follow these instructions:

Login to the mail server using webmail.

Click on Filters from the toolbar menu.

You will be presented with a list of any mail filters that you may have activated on your account. If a spam filter has already been created for you, it will be in the list of filters and called Spam filter. If you don't have such a rule then to create a new spam filter rule, click on New Rule.

The screen will change to display the filter rule entry form. Give your new rule a name by changing the text New Rule to something meaningful e.g. Spam rule.

Now you need to choose how your rule will select the spam messages from your incoming mail.

You need to select on the field X-Spam-Score, which is the score that SpamAssassin (the spam scoring software) will have put in your message headers.

Since this is a number, next select Greater than or equal to (or one of the other numerical comparison operators), and then enter the score that you want to match on e.g. 3. Any messages with a score equal to or greater than 3 will now match this rule.

Now you need to decide what to do with this mail you suspect of being spam. We encourage you to deliver that mail into a folder called suspected_spam. To do so select Deliver to folder and then select a folder name (or create a new one) from the drop-down list that will appear.

You should also check the box to Stop checking if this rule matches, unless you really want the messages to be passed to other filter rules that you may want to apply later in your filter list.

We do not recommend that you automatically delete spam. However, if you create a rule with a very high score to match then you may create a rule that will likely be safe enough to do this.

You can also set up your folder options to automatically expire messages from your suspected_spam folder.

Now press the Save button to activate the spam filter.

Choosing a spam score

You will need to find a score which suits the type of mail you get. You can easily adjust this up and down until you get a good balance between trapping most spam and not mis-directing real mail. We have found that a score of 3 or 4 seems to work for most types of mail.

Checking your spam folder

Please remember to check and clear out your spam folder from time to time. It does count towards your disk quota allocation and it is very likely that some legitimate mail will end up there.

Do make use of the expire message feature.

If you want to find out why a particular message was caught by your spam filter, then you will need to inspect the full headers of the mail message. In the mail header you will see a line beginning with X-Spam-Score.

You can use this to adjust the score you set above. Alternatively, you can use whatever method the mail client you normally use to read mail provides for inspecting the full mail headers of messages; please refer to the documentation provided for each supported mail client.

Whitelists and Blacklists

If you want to bypass the spam scoring mechanism altogether, because you know that you will never receive spam from a particular mail domain e.g. goodguys.org, then you can optionally specify a list of such mail domains in a whitelist rule.

This provides a list of exceptions to any filtering rule. Click on Whitelist in the toolbar.

You should list each mail address or mail domain on a line by itself. The mail domain is the part on the right hand side of the address after the @ symbol. Please note that by specifying a domain you also include any sub-domain e.g. goodguys.org includes badguys.goodguys.org.

Note that if you have incorrectly formatted the mail domains e.g. used a disallowed character, or not put one per line, you will not be able to enable the rule until you correct it.

Note

Any mail matching a whitelisted address will be immediately filed in your INBOX. You should take care to order your rules appropriately so that Vacation messages and spam filtering work in the way you want.

The rule will match not just on the From address but any Resent-From or Sender address too.

This means that it will match on mailing lists that match any address or the address of anyone resending a message to you.

Any messages matching a blacklisted address will be automatically deleted. Use this with care!.