Truth, myths and realities

For a long time it was a known fact that certain ISPs recycled abandoned addresses into spamtraps. There were long discussions by senders about this process and how it happened. Then at a conference a few years ago representatives of ISPs got up and announced that they do not recycle addresses. This led to quite a bit of consternation about how deliverability folks were making things up and were untrustworthy and deceptive.

In the early 2000’s ISPs were throwing a lot of things at the wall to deal with mail streams that were 80 – 90% bulk. They tried many different things to try and tame volumes that were overwhelming infrastructure. ISPs did try recycled traps. I know, absolutely know, two did. I am very sure that others did, too, but don’t have specific memories of talking to specific people about it.
At that time, a lot of deliverability knowledge was shared through word of mouth. That turned into a bit of an oral history. The problem with oral history is that context and details get lost. We can use the story of the ISP that did/did not recycle traps as an example.
Deliverability folks talk about an ISP that recycles traps. They don’t mention how often it happens. Some folks make the assumption that this is an ongoing process. It’s not, but anyone who knows it’s not risks violating confidences if they correct it. Besides, if senders believe it’s an ongoing process maybe they’ll be better behaved. Eventually, the story becomes all ISPs recycle traps all the time. This is our “fact” that’s actually a myth.
Then an ISP employee goes to a conference an definitively states they don’t recycle traps. I believe he stated the truth as he knows it to be. That ISP moved on from recycled traps to other kinds of traps because there were better ways to monitor spam.
We were talking about this on one of the deliverability lists and I told another story.
[ISP] recycled addresses once – back when JD was there which must have been, oh, around 2005/6 or so. I heard this directly from JD. It wasn’t done again, but a whole bunch of people just assumed it was an ongoing thing. Since my knowledge was a private conversation between JD and me, I never felt comfortable sharing the information. Given the circumstances, I’ve decided it’s OK to start sharing that end of the story a little more freely.
No one set out to create a myth, it just happened. No one intended to mislead. But sometimes it happens.

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What makes the best email filter? There isn’t really a single answer to that question. Different people and different organizations have different tolerances for how false positives versus false negatives. For instance, we’re quite sensitive to false positives here, so we run extremely conservative filtering and don’t block very much at the MTA level. Other people I know are very sensitive to false negatives and run more aggressive filtering and block quite a bit of mail at the MTA level.
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.
Then there is mail filtering that doesn’t have to do with spam. Business filters, for instance, often block non-business mail. Permission of the recipient often isn’t even a factor. Companies don’t often go out of their way to block personal mail, but if personal mail gets blocked (say the vacation plane ticket or the amazon receipt) they don’t often unblock it. But when you think about why a business provides email, it makes perfect sense. The business provides email to further its own business goals. Some personal usage is usually OK, but if someone notices and blocks personal email then it’s unlikely the business will unblock it, even if the employee opted in.
In the case of email filters, the free market does work. Different ISPs filter mail differently. Some people love Gmail’s filters. Other people think Hotmail has the best filtering. There are different standards for filtering, and that makes email stronger and more robust. Consumers have choices in their mail provider and spamfiltering.

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Changes at Gmail

As I’ve said before, I can usually tell when some ISP changes their filtering algorithm because I start getting tons and tons of calls about delivery problems at that ISP. This past month it’s been Gmail.
There have been two symptoms I’ve been hearing about. One is an increase in bulk folder delivery for mail that previously was reliably hitting the inbox. The other is a bit more interesting. I’ve heard of 3 different mailers, with good reputations and very clean lists, that are seeing 4xx delays on some of their mail. The only consistency I, and my colleagues at some ESPs, have identified is that the mail is “bursty.”
The senders affected by this do send out mail daily, but the daily mail is primarily order confirmations or receipts or other transactional mails. They send bi-weekly newsletters, though, exploding their volume from a few tens of thousands up to hundreds of thousands. This seems to trigger Gmail to defer mail. It does get delivered eventually. It’s frustrating to try and deal with because neither side is really doing anything wrong, but good senders are seeing delivery delays.
For the bulk foldering, Bronto has a good blog post talking about the changes and offering some solid suggestions for how to deal with them. I’m also hearing from some folks who are reliable that Gmail may be rolling back some of the bulk foldering changes based on feedback from their users.
So if you’re seeing changes at Gmail, it’s not just you.

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Typo traps

People make all sorts of claims about typo traps. One claim that showed up recently was that Spamhaus has just started using typo traps. I asked my Facebook network when people started using typos to detect incoming spam.
Two different colleagues mentioned using typos, both on the left hand side and the right hand side, back in ’98 and ’99.
The point is, typo traps are absolutely nothing new. They are, in fact, as old as spam filtering itself. And as one of trap maintainers remind me, not all of them even look like typos. It’s not as simple as hotmial.com or gmial.com.
I really think that focusing on traps is paying attention to the wrong thing.
The traps are not the issue. The underlying issue is that people are signing up addresses that don’t belong to them. Sometimes those are addresses that are spamtraps. Sometimes those are simply addresses that belong to someone else. Those addresses don’t belong to customers, they belong to random people who may never have heard of the sender. Sending mail to those people is sending spam.
Just trying to remove traps from your address lists isn’t going to solve the underlying problem. Instead, focus on improving your data process to keep from sending mail to random strangers.

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