• by Tom Sather , June 11, 2012

Don’t blame the ISPs for your mail landing in the spam folder.  Blame the spammers.  Over 85% of email received into our network of ISPs around the world is considered spam.  This creates a herculean task for ISPs to ensure that the email ecosphere is safe and trusted, and that good messages get delivered to the inbox and bad ones are blocked or sent to the spam folder.

The spam folder can make or break a business and even careers.  Using content filters, one of the oldest methods to stop spam, requires a lot of user training, is slow, and isn’t scalable.  More importantly, content filters are easily duped by sophisticated spammers and are prone to high false positives.  For most businesses, false positives mean lost revenue and the inability to communicate with customers.  But for a Michigan candidate running for a public post, a false positive meant nearly not making it on the ballot, and a false positive for the Maine GOP caucus nearly caused disenfranchisement.  ISPs know that false positives can have negative consequences, so they really do want to get the right email delivered to the right folder.

The key to stopping spam is in predicting it.  By looking at IP addresses and common sending behaviors, ISPs can stop most spam very quickly.  A quick look in your Gmail inbox with the absence of any spam is a testament to how well reputation filters work. 

Looking at data from Sender Score, similar to a credit score for an IP address (having a range from 0 – 100, with 100 the best) you can see how reputation really does determine what’s delivered to the inbox, the spam folder, or blocked.

1.   Gmail and Hotmail – Having a score above 90 means that about 80% or more of your mail is delivered to the inbox.  A score between 80 and 90 on average has only 62% of email delivered.  A score below 80 has less than 39% inbox placement rates.

2.  Yahoo – A score above 90 has 90% inbox placement rate, a score between 80 and 90 has an 80% rate, and anything below that has a mere 56% chance of reaching the inbox.

A quick look in your spam folder, on the other hand, shows that some emails are still mistakenly being flagged as spam. The key is knowing what data to look at, and then making sure you don’t look like a spammer.

1.   Subscriber complaints – the number of subscribers marking an email as spam is the most common reputation measurement tool.  Most marketing emails struggle with this, as more and more people use the spam button to delete and unsubscribe from mail they signed up for.  Based on the data we see for mailers with the highest deliverability rates, complaint rates should be less than .1%.

2.  Spam traps – The second most accurate predictor of whether or not an email is spam.  Some marketers acquire these through a third party, but most though lax mailing practices where once-real email addresses are converted into spam traps.  Senders with a Sender Score above 90 typically never hit any spam traps. Yes, you read that right: never.

3.  Unknown Users are also a good predictor if an IP address is sending spam or not.  Most marketers typically don’t need to worry about this unless their bounce handling system is broken, they start to mail to addresses they haven’t mailed to in a while, or if they acquire email lists.  The best senders have unknown user rates less than .2%, and major deliverability problems start to occur if you go over 5%.

4.  Sending history – Ever since spammers started hijacking PCs to send spam, ISPs rarely trust a new IP address.  As anyone who has moved to a new ESP or switched to a new IP knows, building up a reputation from scratch can take a long time.  Our data shows that it can take, on average, 30 days to establish a good sending reputation.

So anyone whose business relies on email should do two things:  stop devoting so much effort to bypassing content filters, and focus more on improving one’s sending reputation.   Having a good reputation has the benefit of being able to bypass content filters.  Just ask Pfizer.

The good news is everyone can achieve a great email sending reputation.  Monitor your reputation, look at the right data, and the inbox is yours.