Rather than seeing spam filters as a challenge to be beaten, a more effective use of resources is to make sure your legitimate email is not spam, and that you're not using spammers' techniques, even inadvertently. Not only that, but don't forget the one spam filter you can't fool is the final one - the recipient.
So what can you do to prevent your email being filtered out as spam?
- Follow ISP guidelines. Monitoring the spam filtering policy of every ISP is a mammoth task. There are services you can subscribe to who will do this for you, although you may find that most are focused on the main US ISPs. However, there are steps you can take. For example, if your list is B2C it's likely to include a high proportion of Hotmail, Yahoo and AOL addresses, so at the very least it's worth keeping up with their policies on spam and deliverability. Test different variables, monitor results and stay up to date - as with search engines, the parameters are continuously changing as spammers find ways around them. I recently changed all the calls to action in a customer email so that there wasn't a single 'click here' and the soft bounce rate went down by a third. Coincidence? To get an idea of how the HTML of a message can affect its deliverability, see this article at Clickz.
- Try not to look like spam. For example, make sure your subject line is meaningful or at least recognisable - there's a fine line between 'creative and intriguing' and 'nonsensical and spammy'. The decision to open or delete typically takes less than a second. Obviously spammy words in the subject line may not prevent it entering the inbox, but the email may still end up in a recipient's trash quicker than you can say 'get your free meds here.'
- Adopt email authentication. ISPs are trying to block the professional spammers by only allowing through email that's from who it says it's from. This is something that is only just starting to impact in the UK, but will become increasingly important. It's a whole subject in itself though - to be covered in a future eTip!