Content, trigger words and subject lines

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.

Trigger words are known to cause problems and increase the chances of your email getting caught in a SPAM trap. By avoiding these words in your email subject lines, you can dramatically increase your chances of getting beyond SPAM filters.

OK, so I’m not sure about the “dramatic” part, as some of the words they list as triggers in the subject lines will also trigger scores when used in the body of the message. But the gist of the Hubspot post is not wrong. If you use too many words and phrases used by spammers, then your mail is going to be difficult to distinguish from spam. I don’t think this is actually controversial (although I’ve been known to be wrong…)
But some of the comments on the post go too far in the other direction and totally misrepresent reality.

Content filtering hasn’t been a big component of spam filtering algorithms for nearly a decade.

This is blatantly and demonstrably untrue. Naive content filtering hasn’t been a big component for nearly a decade, but content filtering is where filtering is going. IP based filtering is good for some things but content filtering allows for much finer grained sorting and filtering. I think content filtering is where the industry is going. Too many spammers have created too many ways to avoid and subvert IP based filters for them to be the full solution to protecting users.
Content matters, don’t think it doesn’t. But don’t let word lists like the above frighten you off from crafting good subject lines.

Return Path acquires OtherInbox
Delivery versus marketing

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Some people think FBLs are the best thing since sliced bread and can’t figure out why more ISPs don’t offer them. These people use use the data to clean addresses off their lists, lower complaints and send better mail. They use the complaints as a data source to help them send mail their recipients want. Too many recipients opted out on a particular offer? Clearly there is a problem with the offer or the segmentation or something.
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Sadly, I’m not actually making up the terminology in the last paragraph. There really are who think that the problem isn’t with the mail that they’re sending but that the recipients can actually express an opinion about it and the ISPs listen to those opinions. “Terrorists” and “Nazis” are the least of the things they have called people who complain about their mail.
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One of the most common things I hear is “but why does the ISP do it that way?” The generic answer for that question is: because it works for them and meets their needs. Anyone designing a mail system has to implement some sort of spam filtering and will have to accept the potential for lost mail. Even the those recipients who runs no software filtering may lose mail. Their spamfilter is the delete key and sometimes they’ll delete a real mail.
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For the major ISPs, the people who plan, approve, design and monitor the filters usually want to maximize customer happiness. They want to deliver as much real mail as possible while blocking as much bad mail. Blocking real mail and letting through bad mail both result in unhappy customers and increase the ISP’s costs, either through customer churn or through support calls. And this is a process, filters are not static. ISPs roll out new filters all the time, sometimes they are an improvement and sometimes they’re not. When they’re not, they’re pulled out of production. This works both for positive filters like Return Path and negative filters like blocklists.
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