Why am I still getting spam? – An insight into spam filters

Posted on Apr 26, 2016 in Security, WatchGuard

Why am i still getting spam

Throughout the world over 54 million spam emails are sent every day ranging from dream job offers through to emails from your bank asking you to update your details. We’re so much more aware of it now that our not so friendly spammers are going to even greater, and sometimes humorous, lengths to catch you out.

Some of the subject lines such as “this is a legitimate business transaction” and “good earnings in the international company” we know you’ll just scoff at and delete, but the more crafty ones are creating heightened risk.

Spam is a BIG problem. Last month alone 352,496 spam emails were targeted at our clients. Of the 433,074 emails that were sent only 18% were recognised as legitimate email.

March spam filter results

So how does a SPAM filter work?

Not all SPAM is created equal, in fact there is a rating system for spam. For an email to be considered legitimate it needs to pass a set of criteria. Each criteria is weighted depending on the threat level if the email doesn’t pass a particular requirement.

In general a spam filter will assess three areas

  1. where the email came from
  2. what software sent the email, and
  3. what content is contained within the email.

If an email ‘passes’ all the criteria it will be delivered straight to your inbox.

But if it matches’ some of the criteria to mark it as problematic, or just one particularly bad one, then it will either be discarded never to be seen again or it will be sent to a quarantine to be evaluated for release or dismissal.

Here’s a sample summary of an email assessment made by our spam filter.

Sample spam filter

Why am I still getting so much of it?

Spam filters are getting so good that the spammers are constantly finding new ways around them with new tricks and ‘work arounds’ being developed daily, and with the sheer volume that is sent a small amount does get missed.

“The arms race between malware authors and security software developers is fraught with new and undetectable strains of malware making an appearance every day, and staying on top of it is a challenge” – Simon Falconer

Read more at Security Brief NZ

You may also be employing some methods that spammers love such as listing your email address publically on your website. Spammers have programmes that crawl the internet scanning for email addresses and collect yours to add to their growing list.

5 actions to reduce the amount of SPAM you receive

  • Report the email as spam – some email services will have a ‘report as spam’ button. This will help build a cache of information for the email provider to prevent further attacks.
  • Keep your email private – when using social media sites, message boards or chat rooms use a secondary email account you’ve set up for public use.
  • Never reply – spammers see replies as verification that your email is active, which could lead you to receiving even more.
  • Use a service with a good email filter – as you can see from the images above a filter will catch the majority if not all SPAM.
  • Read the privacy policies – ensure that when you submit your email address to win, subscribe or download a product/service that you aren’t handing over permission for the company to sell your email address.

The primary rule with spam – if in doubt – trash the email, and if you’re one of our customers you can also forward us the email or the email address so we can improve our filters.

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