Getting past spam filters

We want spam filters to work well saving our time and bandwidth from this unnecessary waste.  According to the Google enterprise and archiving security network Postini, for the first quarter of 2009, around 94 percent of all e-mail sent to their customers was spam.

On the other hand, we want our normal business correspondence to get through. Especially marketing and promotional emails that our customers have asked for and subscribed to.

Therefore it pays to understand how emails are screened, rejected or accepted.

  • The newer your email software, the more advanced the filtering will be.
  • Lists of known spammers or the Internet Service Provider (ISP) they use comprise Blacklists. Your ISP will deny messages coming from an entity on the blacklist. The bad news is all innocent clients of blacklisted ISP’s get blocked too.
  • Greylisting is when an ISP temporarily rejects all incoming email, anticipating that non-spamming sources will re-send the delayed email in a few seconds, minutes or hours. Your problem – the delivery of your email is held up in this process too.
    • Spam filters also intricately examine the words and the technical composition of each email, primarily working on a point scoring system. It is up to each company’s discretion how strict or lenient they set the filter.
      • An extensive list of what Spam Assassin looks at is found on http://au2.spamassassin.org/tests.html. For example points are taken away for:
      • Large sized or non standard font colours
      • Message has x% of HTML code
      • Message has click here
      • Pass, forward on
      • For free
      • Order today, order now
      • Money back guarantee

Unfortunately, there is no magic bullet to get past the filters, except to be as circumspect as possible I’m afraid.

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