Feedback loops

There are a lot of different perspectives on Feedback Loops (FBLs) and “this is spam” buttons across the email industry.
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.
Other people, though, think the existence of “this is spam” buttons and FBLs is horrible.  They call people who click “this is spam” terrorists or anti-commerce-net-nazis. They want to be able to dispute every click of the button. They think that too many ISPs offer this is spam buttons and too many ESPs and network providers pay way to much attention to complaints. The argue ISPs should remove these buttons and stop paying attention to what recipients think.
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.
One of the senior engineers at Cloudmark recently posted an article talking about FBLs and “this is spam” buttons. I think it’s a useful article to read as it explains what value FBLs play in helping spam filters become more accurate.

We have found over time that the most effective systems are those that learn to classify undesirable content based on feedback from users. The user is truly the best judge of what is and isn’t spam. The faster that consistent feedback becomes available, the sooner a filter can be re-trained to detect and respond to new attacks.

Spam filters are not there to stymie senders, their real job is to protect recipients. Faster adapting filters may seem like a bad thing, but they adapt in both directions. Send good mail that people want and it gets through. Send bad mail that people complain about and filters quickly adapt to block it.

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Gmail and the PBL

Yesterday I wrote about the underlying philosophy of spam filtering and how different places have different philosophies that drive their filtering decisions. That post was actually triggered by a blog post I read where the author was asking why Gmail was using the PBL but instead of rejecting mail from PBL listed hosts they instead accepted and bulkfoldered the mail.
The blog post ends with a question:

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Why do ISPs do that?

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.
Every mailserver admin, whether managing a MTA for a corporation, an ISP or themselves inevitably looks at the question of false positives and false negatives. Some are more sensitive to false negatives and would rather block real mail than have to wade through a mailbox full of spam. Others are more sensitive to false positives and would rather deal with unfiltered spam than risk losing mail.
At the ISPs, many of these decisions aren’t made by one person, but the decisions are driven by the business philosophy, requirements and technology. The different consumer ISPs have different philosophies and these show in their spamfiltering.
Gmail, for instance, has a lot of faith in their ability to sort, classify and rank text. This is, after all, what Google does. Therefore, they accept most of the email delivered to Gmail users and then sort after the fact. This fits their technology, their available resources and their business philosophy. They leave as much filtering at the enduser level as they can.
Yahoo, on the other hand, chooses to filter mail at the MTA. While their spamfoldering algorithms are good, they don’t want to waste CPU and filtering effort on mail that they think may be spam. So, they choose to block heavily at the edge, going so far as to rate limit senders that they don’t know about the mail. Endusers are protected from malicious mail and senders have the ability to retry mail until it is accepted.
The same types of entries could be written about Hotmail or AOL. They could even be written about the various spam filter vendors and blocklists. Every company has their own way of doing things and their way reflects their underlying business philosophy.

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Spamfilters: a marketer's best friend

I was cleaning out my spam folder this afternoon. I try and do it at least once a day, otherwise the volume gets so bad I don’t actually look at the mail I just mark it all as read. I realized, though, that spamfilters are actually a marketer’s best friend.
If there were no spam filters keeping all the crap people get out of their inbox (in my case over 1000 messages a day) then spam would overwhelm even the most dedicated email junkie. I couldn’t do my job without my spam filters, and in fact the recent rash of virus spew is ending up in my inbox and making finding real mail a problem. I do a lot of sorting before mail ever hits my inbox, and I’m still struggling to deal with the couple hundred “your order has shipped!” and “please her tonight!” emails that my local bayesian filters haven’t caught up to, yet.
Today’s stats:
Work inbox: 17 messages
Work spam: 419
95.9% spam
Personal inbox: 40
Personal spam: 975
95.9% spam
Without filters, I couldn’t accurately find that 4.1% of real mail that I get. Without filters, I couldn’t do my job. Without filters, I couldn’t find the real receipts from purchases I actually made. Without filters, I couldn’t read and respond to mail I wanted.
A mailbox overflowing with spam is unuseable, and email marketers should be thankful that providers work so hard to keep spam out. Otherwise, email wouldn’t be useful for anything.

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