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Reputation

Reputation is the buzzword in delivery these days. Everyone talks about building a good reputation and how to do it. Makes sense, the ISPs are always hammering on reputation and how critical reputation is. The more I talk with delivery folks on the ESP side of thing, the move I realize that there is a fundamental disconnect between what the ESPs mean when they say reputation and what the ISPs mean when they say reputation.
Many people handling delivery think that the bulk of reputation is wrapped up in complaint rates and bounce rates. I think they know the ISPs measure more than just complaints and bounces (spamtraps!) but really believe that most of developing a good reputation is all about keeping those complaints low.
This perspective may have been true in the past, but is becoming less true as time goes on. There are a lot of very smart people managing incoming mail at the ISPs and they are constantly looking for ways to better meet the desires of their customers. Lest we forget, their customers are not the senders, their customers are the end users. Their customers are not senders.
Part of meeting the needs of end users means actually giving them a way to provide feedback. AOL started the trend with the this-is-spam button, and other ISPs (ones that controlled the user interface at least) followed suit. For a very long time, reputation was dominated by complaint percentages, with modifiers for number of spamtrap addresses and number of non-existent users.
The problem is, these numbers were easy to game. Spammers could modify their metrics such that their email would end up in the inbox. In response, the ISPs started measuring things other than complaints, bounces and spamtraps. These other measurements are strong modifiers to complaints, such that mailers with what used to be acceptable complaint rates are seeing their mail end up bulked or even rejected.
Recently, AOL seems to have made some subtle modifications to their reputation scores. The result is mailers who have previously acceptable complaint rates are seeing delivery problems. When asked, AOL is only saying that it is a reputation issue. Lots of senders are trying to figure out what it is that is more important than complaints.
Tomorrow, I will talk about what I think AOL could be measuring.

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Spamtraps

There is a lot of mythology surrounding spamtraps, what they are, what they mean, how they’re used and how they get on lists.
Spamtraps are very simply unused addresses that receive spam. They come from a number of places, but the most common spamtraps can be classified in a few ways.

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20% of email doesn't make it to the inbox

Return Path released their global delivery report for the second half of 2009. To put together the report, they look at mail delivery to the Mailbox Monitor accounts at 131 different ISPs for 600,000+ sends. In the US, 20% of the email sent by Mailbox Monitor customers to Return Path seed accounts doesn’t make it to the inbox. In fact, 16% of the email just disappears.
I’ve blogged in the past about previous Return Path deliverability studies. The recommendations and comments in those previous posts still apply. Senders must pay attention to engagement, permission, complaints and other policy issues. But none of those things really explain why email is missing.
Why is so much mail disappearing? It doesn’t match with the philosophy of the ISPs. Most ISPs do their best to deliver email that they accept and I don’t really expect that ISPs are starting to hard block so many Return Path customers in the middle of a send. The real clue came looking at the Yahoo numbers. Yahoo is one of those ISPs that does not delete mail they have accepted, but does slow down senders. Other ISPs are following Yahoo’s lead and using temporary failures as a way to regulate and limit email sent by senders with poor to inadequate reputations. They aren’t blocking the senders outright, but they are issuing lots of 4xx “come back later” messages.
What is supposed to happen when an ISP issues a 4xx message during the SMTP transaction is that email should be queued and retried. Modern bulk MTAs (MessageSystems, Port25, Strongmail) allow senders to fine tune bounce handling, and designate how many times an email is retried, even allowing no retries on a temporary failure.
What if the missing mail is a result of senders aggressively handling 4xx messages? Some of the companies I’ve consulted for delete email addresses from mailing lists after 2 or 3 4xx responses. Other companies only retry for 12 – 24 hours and then the email is treated as hard bounced.
Return Path is reporting this as a delivery failure, and the tone of discussion I’m seeing seems to be blaming ISPs for overly aggressive spamfiltering. I don’t really think it’s entirely an ISP problem, though. I think it is indicative of poor practices on the part of senders. Not just the obvious permission and engagement issues that many senders deal with, but also poor policy on handling bounces. Perhaps the policy is fine, but the implementation doesn’t reflect the stated policy. Maybe they’re relying on defaults from their MTA vendor.
In any case, this is yet another example of how senders are in control of their delivery problems. Better bounce handling for temporary failures would lower the amount of email that never makes it to the ISP. This isn’t sufficient for 100% inbox placement, but if the email is never handed off to the ISP it is impossible for that email to make it to the inbox.

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