Email Filtering

CampusNet includes Watchdog’s MailWatch service that provides email filtering totally externally to the school server.

As a result, our email filtering is compatible with most email clients that the school may have, even if their mail is hosted with another ISP besides Watchdog. This is facilitated through a change to the primary MX record on the DNS servers that host the school’s domain name to tell the mail to be routed to our mail filters prior to delivery to their mail server or ISP’s mail server.

This service requires the school to have their own domain name e.g. @schoolname.school.nz. If you use your Internet providers domain, such as schoolname@xtra.co.nz, this cannot be supported by our service. NZ domain names are available from Watchdog at $29 setup plus $10 per month if required (prices exclude GST).

MailWatch is a custom-developed system based on SpamAssassin, a mail filter to identify spam. Using its rule base, MailWatch uses a wide range of heuristic tests on mail headers and body text to identify “spam” (also known as unsolicited commercial email). Once identified, the mail is then tagged as ‘spam’ or ‘possible spam’. You can then choose what you would like done with these emails. Spam emails can be redirected to a specific email address or deleted if you wish. We do not block emails we only filter them.

Features and benefits of MailWatch

• Keyword Filtering – emails can be filtered out based on foul language or chosen content to minimise offensive or unproductive email.
• Attachment filtering – MailWatch scans attachments for foul language and file type. Malicious and unwanted attachments can be filtered and automatically deleted on request, reducing network congestion and the risk of viruses.
• Virus filtering – MailWatch identifies viruses in emails based on their signature and filters and labels as SPAM before they reach your network.
• SPAM Filter – Unwanted mail can be labelled as SPAM, reducing time wastage and network congestion.
• ‘White Listing’ – Known good sources of email can be added to the filter to minimise the risk of wanted emails being labelled as SPAM and filtered as such.

Spam message labelling

MailWatch assigns a spam rating number to each email message, depending on its score through the analysis process. This score is used to categorise emails into three groups – Not Spam, Possibly Spam or Spam.

Emails designated as Spam can be deleted, forwarded to an administrator email address or forwarded to the recipient. A school may choose which option they would like.

A typical installation would involve the customer configuring an email address on their mail server, such as spam@whatever.school.nz, and we would use this address for forwarding emails for checking. We will usually forward all Spam labelled messages to this address for a few weeks to ensure that no messages are being categorised incorrectly and, once that period is up, these messages can be deleted if the school wishes. (School must advise once messages are being categorised correctly)

We will generally forward all Possibly Spam labelled messages to the recipient unless the school specifies that these are to go to an administrator email address.

Managing SPAM

We do our best to keep SPAM under control but Spammers are becoming increasingly clever. Here’s some things you can do to minimise this problem:

Set up your email program to move your labeled Spam/Possibly Spam to another folder

• For Microsoft Outlook, use these steps:
• Create a new folder in your email inbox and label it ‘SPAM’
• Go to ‘Tools and select ‘rules and alerts’
• Click on ‘New Rule’
• Click on ‘Move messages with specific words in the subject to a folder’
• Click on ‘specific words’ in the bottom white box and enter ‘SPAM’ or ‘POSSIBLY SPAM’ and click ‘add’ then ‘OK’
• On the bottom white box click on ‘specified folder’ and choose the SPAM folder that you have just set up and click ‘ok’
• Click ‘next’ then ‘finish’ then ‘apply’
• Click ‘ok’

For Microsoft Outlook Express, use these steps:

• Create a new folder in your email inbox and label it ‘SPAM’
• Go to ‘Tools’ and select ‘ Message Rules’
• Click on ‘Mail’ then ‘New’
• Tick the box that says ‘Where the subject line contains specific words’
• In bottom box click on ‘contains specific words’ and type in ‘SPAM’ or ‘POSSIBLY SPAM’
• Click ‘ok’
• In the middle box (select the actions for your rule) select ‘Move it to the specified folder’
• In bottom box click on ‘specified folder’and choose the SPAM folder that you have just set up and click ‘ok’
• Click ‘ok’ then ‘ok’ again

If possible get us to block ‘Spam’ for your school… email blockspam@watchdog.net.nz
Make sure your school does not have a ‘catchall’ on it’s domain (this is open access for Spammers). Get us to check this for you
Make sure your mail server is only receiving mail from our Spam filters (IP range 202.89.50.45 through to 202.89.50.55). Check this out with your technician.