Take downs of prolific spam botnets, such as Rustock in 2011
and Grum in 2012
, had a substantial effect on reducing overall global spam volumes. This, combined with diminishing returns for spammers sending via bots, had left many email recipients basking in the comfort of (mostly) clean inboxes. No doubt this downward trend in global spam volumes also saved countless pounds that would have otherwise been frittered away on phony school fees and suspect weight loss products.
Unfortunately, however, the good times seem to be coming to an end. Spam volumes have increased to the point that spam is now at its highest level since late 2010. Below is the graph of global spam volume as reported by SenderBase. From June 2014 to January 2015, spam was averaging between 50-100 billion messages per month, but as of March 2015 volumes were peaking above 200 billion messages per month–more than a 2X increase above normal.
Sophos isn’t the only organisation noticing the increase in spam volume. Several other organisations that are in a position to track trend data also published similar looking graphs. For example, below is a graph of the past three years’ total spam volume as reported by the Composite Block List (CBL). In fact you have to go back all the way to October 2010 to see comparable spikes in volume.
When spam volumes increase globally, we all notice the additional spam hitting our inbox. For example, imagine an anti-spam filter that is 99.9% effective at stopping spam. If spammers send 1000 spam messages, the filter should successfully banish about 999 of them to the spam folder, but one of the spam messages will inevitably pass through to the inbox; no filter is perfect. Now imagine that instead of sending 1000 spam messages, the spammers send 2000.
The amount of spam in the inbox will have just doubled too! This is a simple example, but it illustrates the effect increased spam volumes have in the real world. While we haven’t reached the record levels of spam seen during the heyday of spamming botnets, increases in spam volumes can be problematic nonetheless. With this increase, organisations should also understand that the extra unsolicited email could obscure more threatening emails like spearphish.
At Sophos they are constantly devising new and clever ways to put the kibosh on spam. As a result of their efforts, Sophos Anti-Spam technology continues to be one of the most effective ways of filtering unwanted email from your inbox, providing the best possible protection to "ride out the storm.”
More you can do to stop spam
- Don't reply to spam messages. Replying confirms that your email is valid, and will probably result in you receiving more spam.
- Don't spread spam.
- Don't hesitate to use the delete key. The most reliable way to rid yourself of spam is to delete it.
This is a guest blog post written by David Thompson who is the current IT Manager for WCF Ltd. David will be writing a monthly article as part of the "IT Corner" column / slot. We hope you find these snippets of IT knowledge useful!