More about e-mail service and spam
We are glad to report that our e-mail service, which had been sluggish earlier this semester, is now performing well again. Whilst there were a few factors at play, the sluggishness was attributable primarily to our spam-checking mechanisms that we are reviewing now on a regular basis.
Those of you who take an interest in these things will know that spam has changed its characteristics in the past few months. According to spam-filtering company IronPort Systems, it has doubled from last year to this year, and now represents more than 90 percent of all e-mail traffic.
Much of the increase is attributable to ‘image’ spam, which has quadrupled over the same period of time and now accounts for between 25 and 45 percent of all spam. With image spam, text is converted to graphics, which can be read by individuals who receive them but not by spam filters on the lookout for words and phrases that can identify a message as spam. The recent rise in spam comes after the passage in 2003 of US federal legislation intended to limit junk e-mail and a prediction by Microsoft Chairman Bill Gates that same year that the problem of spam “will be solved by 2006.” Well, there are still a few days to go...
For more information, see, for example:
http://news.com.com/2100-7355_3-6141262.html
Some figures might give an idea of the scale of the problem as it affects us locally, and of the change since this time last year. In December 2005 about 100,000 messages were hitting our mail servers every day; this has roughly doubled with the number currently running at between 190,000 and 210,000 or more.
We now reject outright approximately 60% of all messages on the basis of blacklists of known senders of spam. This means about 120,000 spam messages that never reach anyone’s mailbox. Twelve months ago the proportion of messages caught by the blacklists was about 43%.
Of the messages accepted after the blacklisting process, we are tagging about 56% as spam; this means about 44,000 messages that are identified as spam, and which users can therefore filter easily out of their mailboxes. The corresponding percentage in December 2005 was 31%.
The conclusion is that however annoying you might find the spam that reaches your mailbox, there is much more that doesn’t get through to you. The situation is always changing, and IT Services will need to keep alert for changes. Since there is always some spam getting through you should consider the further line of defence provided by the adaptive filters in e-mail clients such as Thunderbird; see the article on this in the November issue of the Newsletter.
Average daily figures for blacklisted, tagged and untagged in mid December in 2006 and 2005 are shown below:
2006 |
2005 |
|
blacklisted |
117413 |
41393 |
tagged as spam |
44353 |
17119 |
accepted untagged |
35922 |
38448 |
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