Recent Posts

Greylisting: that which Yahoo does not do

Over the last couple days multiple people have asserted to me that Yahoo is greylisting mail. The fact that Yahoo itself asserts it is not using greylisting as a technique to control mail seems to have no effect on the number of people who believe that Yahoo is greylisting.
Deeply held beliefs by many senders aside, Yahoo is not greylisting. Yahoo is using temporary failures (4xx) as a way to defer and control mail coming into their servers and their users.
I think much of the problem is that the definition of greylisting is not well understood by the people using the term. Greylisting generally refers to a process of refusing email with a 4xx response the first time delivery is attempted and accepting the email at the second delivery attempt. There are a number of ways to greylist, per message, per IP or per from address. The defining feature of greylisting is that the receiving MTA keeps track of the messages (IP or addresss) that it has rejected and allows the mail through the second time the mail is sent.
This technique for handling email is a direct response to some spamming software, particularly software that uses infected Windows machines to send email. The spam software will drop any email in response to a 4xx or 5xx response. Well designed software will retry any email receiving a 4xx response. By rejecting anything on the first attempt with a 4xx, the receiving ISPs can trivially block mail from spambots.
Where does this fit in with what Yahoo is doing? Yahoo is not keeping track of the mail it rejects and is not reliably allowing email through on the second attempt. There are a couple reasons why Yahoo is deferring mail.

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40 email companies

Ken Magill has a post up mentioning the top 40 companies in email marketing. Some highlights:

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ISP Postmaster sites

A number of ISPs have email information and postmaster sites available. I found myself compiling a list of them for a client today and thought that I would put up a list here.

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How to improve AOL delivery

DMNews interviewed Charles before he left AOL about the state of spam and the challenges for ISPs and how that affects senders. The article was published this week. In it he talks about

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Spam in the workplace

In comments on my last post Lux says:

It seems to me that in regard to PR people sending press releases to a professional journalist, you’ve got a very specific use case with slightly different rules of engagement from the norm.

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Wired editor has enough spam!

Seth Godin links to a post up over on The Long Tail about spammers who send PR mail to Chris Anderson, an editor at wired. Apparently lots of people send automated email to the editor of Wired hawking their latest and greatest product, service or photos.
In response to this overwhelming amount of mail, Chris has instituted a new email acceptance policy. He says

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New VP at Goodmail

Charles Stiles, who managed the postmaster team at AOL and was laid off 2 weeks ago, is the new VP of Worldwide Business Development at Goodmail.
Ken Magill mentioned the possibility of Charles moving to Goodmail yesterday.

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Do open rates matter?

Ken Magill over at DirectMag has an article deriding the reliance on ‘open rates’ as a metric for the success (or failure!) of marketing campaigns.

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DKIM "i=" vs "d=" and Reputation

This really should be part seven of a twelve part series or some such as it deals with an aspect of DKIM that’s really important, but is way down in the details of implementation. (dkim.org is a reasonable place to start for a general overview of DKIM).
There’s an apparently endless thread on the DKIM-SSP spec development mailing list at the moment about the differences between two fields in a DKIM signature that could be used to tie a senders reputation to. Several ESP delivery folks asked me to explain what everyone was talking about, and this post is a first cut at that.
“i=” vs “d=”
There are two possible fields in a DKIM signature that could be used to identify the sender of a message, and so to tie a sender history and reputation record to. They are the so-called “i=” and “d=” field, from the syntax used to include them in the signature.

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Experience as a recipient

One of the challenges of my job is to separate my personal feelings and experiences related to email marketing and spam from my advice to clients. I am here to make your delivery better, not to make everyone use email marketing the way that makes me the most comfortable.
That being said, I get a lot of spam across my various email addresses. If I have an extra few minutes I’ll sometimes send complaints, but more and more it is too hard, too complicated and / or the ISPs do not care anyway. In the last 2 weeks I’ve had 3 experiences with unexpected / unwanted email (aka: spam) where I did take action.

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