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IT Services offers server
side filtering for unwanted e-mail or spam. Members of staff and students with an IT Services e-mail
address can manage spam messages more efficiently using this spam filter facility. This system
does not involve installation of software on the user's computer system.
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By default, the spam filter facility is
not enabled. Users are instructed to read through the following information and the content of the
Web pages indicated at the end of this page, before enabling the spam filter.
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Features of the Spam Filter
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- The software scans incoming messages,
looking for specific words or phrases (spam signatures) which are known to occur in spam.
Each message is assigned a score (point) value based on the identified spam signatures.
If the score is higher than a particular value known as the threshold value, the message
will be classified as 'spam'.
The scanning of messages is an automated
process entirely done by the spam filter program on the IT Services server. It does NOT in
any way involve a person/s reading any other person's e-mail messages! The spam filtering
software being used on IT Services mail servers is SpamAssassin.
- The spam filter (when enabled) will not
deliver spam messages to the recipient's mailbox. Spam messages are blocked and stored on
the IT Services server for 30 days. Users will receive a daily e-mail report listing the details of
the quarantined messages. The recipients are able to retrieve any quarantined message stored
on the IT Services server to his/her mailbox.
The spam filter can alternatively be configured
to tag (label) spam messages by inserting the word {Spam?} in the subject line. The tagged messages
are delivered along with other incoming messages to the recipient's mailbox. Users opting
for this configuration (not recommended) will also need to set filter/message rules on their
e-mail program (Mozilla, Netscape, Outlook Express etc.) so that tagged messages are automatically
moved to a separate folder.
- Users can also specify a list of e-mail
addresses known as a blacklist. Messages sent from blacklisted senders are blocked and
stored on the IT Services server.
- Users can also specify a list of e-mail
addresses known as a whitelist. Messages sent from whitelisted senders are not classified
as spam, even though these may have spam content.
- The sensitivity level of filtering or threshold
value may be customised by users as appropriate. Low threshold values will classify more messages
as 'spam'. However, users should be cautious about low threshold values because most of their genuine mail
will end up being blocked by the spam filter.
- Messages originating from the campus network
passing through the IT Services mail servers are never classified as 'spam'.
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spam filter deletes messages with a score (point) value above 20. Other
messages with score values between the threshold (set by the user)
and 20 are blocked & stored on the IT
Services server. All blocked emails can be retrieved from the IT
Services server at any time within 30 days. Blocked messages are
deleted from the IT Services server after 30 days.
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The spam filter
may occasionally classify a legitimate and potentially important message as 'spam'; a so called
'false positive'. Accordingly, it is the responsibility of the user to routinely review the
daily e-mail report listing the quarantined messages.
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It is important to note that the IT Services spam filter service
is just a part of the effort required to help users deal with spam. Users are
also encouraged to follow the anti-spam guidelines indicated
here.
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Other Information
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Queries about the spam filter facility should be directed here.
- Last updated: 31-Oct-07
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