Return Path have an interesting post up about content filtering. I like the model of 3 different kinds of filters, in fact it’s one I’ve been using with clients for over 18 months. Spamfiltering isn’t really about one number or one filter result, it’s a complex interaction of lots of different heuristics designed to answer the question: do recipients want this kind of mail?
There’s been quite a bit of traffic on twitter this afternoon about a recent blog post by Hubspot identifying trigger words senders should avoid in an email subject line. A number of email experts are assuring the world that content doesn’t matter and are arguing on twitter and in the post comments that no one will block an email because those words are in the subject line.
As usually, I think everyone else is a little bit right and a little bit wrong.
The words and phrases posted by Hubspot are pulled out of the Spamassassin rule set. Using those words or exact phrases will cause a spam score to go up, sometimes by a little (0.5 points) and sometimes by a lot (3+ points). Most spamassassin installations consider anything with more than 5 points to be spam so a 3 point score for a subject line may cause mail to be filtered.
The folks who are outraged at the blog post, though, don’t seem to have read the article very closely. Hubspot doesn’t actually say that using trigger words will get mail blocked. What they say is a lot more reasonable than that.
In addition to posting some of my thoughts about how delivery and marketing have different and possible contradictory constraints, I asked folks on the Only Influencers list what they thought. They had some different perspectives, primarily being marketers. One person even welcomed me to the dark side.
The general response from the marketing side of things appeared to be that ISPs need to stop actually filtering marketing email. That would resolve the problems from the marketers perspective. I don’t necessarily think that will help. I believe if marketers had unfettered access to the inbox, most inboxes would be totally un-useable.
My thinking triggered other folks to consider delivery and marketing and what drives both. George Bilbrey, from Return Path, posted an article in Mediapost looking at why good delivery is an important part of a good marketing strategy.
George points out many marketers really do act as if delivery is separate and detrimental to good marketing.
Return Path published their most recent Global Deliverability report this morning. (Get the Report) This shows that inbox placement of mail has decreased 6% in the second half of 2011. This decrease is the largest decrease Return Path has seen in their years of doing this report.
To be honest, I’m not surprised at the decrease. Filters are getting more sophisticated. This means they’re not relying on simply IP reputation for inbox delivery any longer. IP reputation gets mail through the SMTP transaction, but after that mail is subject to content filters. Those content filters are getting a lot better at sorting out “wanted” from “unwanted” mail.
I’m also hearing a lot of anecdotal reports that bulk folder placements at a couple large ISPs increased in the first quarter of 2012. This is after the RP study was finished, and tells me increased bulk folder placement is more likely to be a trend and not a blip.
One of the other interesting things from the RP study is that the differences are not across all mail streams, but are concentrated in certain streams and they vary across different regions.