Author: steve


On Friday I talked a bit about the history behind TXT records, their uses and abuses. But what’s in a TXT record? How is it used? When and where should you use them? Here’s what you get if you query for the TXT records for from a unix or OS X command line with dig […]


A brief history of TXT Records

When the Domain Name System was designed thirty years ago the concept behind it was pretty simple. It’s mostly just a distributed database that lets you map hostname / query-type pairs to values. If you want to know the IP address of, you look up {, A} and get back a couple of IP addresses. […]

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IPv6 Email is a little different

On Monday I talked about how big IPv6 address space is, and how many IPv6 addresses will be available to end users. We’re mostly an email blog, though, so what’s the relevance to sending email? If the recipient you’re sending to has an IPv6 mailserver you can send mail to them over IPv6, if you […]


IPv6 is big

IPv6 is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to IPv6. The old Internet, the one you’re probably using right now, runs on IP version 4. IPv4 addresses have […]


On Father’s Day

I’m on quite a few mailing lists for companies whose main product is sending gifts: food hampers, jewelry, flowers, overpriced desk toys and so on. They tend to ramp up their volume before appropriate holidays such as Christmas, Mother’s Day, Thanksgiving, Valentine’s Day or Father’s Day and target their promotions to those particular holidays. One […]

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Google Apps for ISPs is gone

Google Apps for ISPs is being shut down. While this was a scheduled end of life, apparently some users weren’t notified (always keep the contact email address up to date at your vendor!) and other users were told that it would be discontinued in July and were surprised when their service was turned off a month earlier […]


iCloud Postmaster resources

iCloud Mail (,, has a shiny, new postmaster resources page. No whitelist, no FBL, just a good list of best practices to follow for sending bulk mail.

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Political Fraud & Spam

The Conservative Party is one of the largest political parties in the UK. They’re center-right politically (by European standards), nationalist and pro-business. You’ll often see them called the Tory party or Tories – a pejorative nickname they acquired 350 years ago. While they’re part of the ruling coalition today, there’s a general election coming up in the […]

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Authentication and Repudiation

Email Authentication lets you demonstrate that you sent a particular email. Email Repudiation is a claim that you didn’t send a particular email.   SPF is only for email authentication1 DKIM is only for email authentication DMARC is only for email repudiation   1 SPF was originally intended to provide repudiation, but it didn’t work reliably enough to […]


Yahoo FBL Down

We’re seeing multiple reports that the Yahoo feedback loop stopped working some time in the past couple of days. If you’re not seeing reports, it’s not just you.

  • Lost in the mists of time

    Over on the Farsight Security blog Joe St. Sauver talks about some of the early days of online abuse, on usenet. Laura and I were on the periphery of early usenet abuse, mostly as users, but Usenet (and IRC) around then were the places we both started with email abuse.No Comments

  • Ongoing Yahoo delays

    I've been hearing from folks over the last few days that they're seeing an uptick in deferrals from Yahoo! The deferrals are not uniform. ESPs report they're seeing some, but not all, customers affected. Other ESPs aren't seeing any changes. It's not just you. But it would be very worthwhile to dig into engagement and other stats. It's possible this is a new normal at Yahoo! and they're tightening filters to catch mail that doesn't fit their standards but was previously difficult to filter.No Comments

  • AOL starts using Sender Score Certification

    Good news for Sender Score Certified IPs. Return Path recently announced that AOL has joined the list of ISPs offering preferential treatment to certified IPs.  1 Comment