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Author: steve

Captchas

Captchas – those twisty distorted words you have to decipher and type in to access a website – have been around since the 1990s. Their original purpose was to tell the difference between a human user and an automated system, by requiring the user to answer a challenge – one that was supposedly hard for […]

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SPF and TXT records and Go

A few days ago Laura noticed a bug in one of our in-house tools – it was sometimes marking an email as SPF Neutral when it should have been a valid SPF pass. I got around to debugging it today and traced it back to a bug in the Go standard library. A DNS TXT […]

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Good morning DMARC

I’m thinking I may need to deploy DMARC report automation sooner rather than later. … and so on, and on, and on for a lot further down the mailbox.

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DNS Flag Day

There are quite a lot of broken DNS servers out there. I’m sure that’s no surprise to you, but some of them might be yours. And you might not notice that until your domains stop working early next year. DNS is quite an old protocol, and when it was originally specified there wasn’t really a […]

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Check your abuse addresses

Even if you have excellent policies and an effective, empowered enforcement team you can still have technical problems that can cause you to drop abuse mail, and so lose the opportunity to get a bad actor off your network before they damage your reputation further. It’s not quite as simple as “We’re seeing email in […]

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Your idea will not work. Here is why it won’t work.

Matthew Green reminded me of an old bit of spam lore. It’s a canned response to someone’s New and Awesome and entirely unoriginal Final Ultimate Solution to the Spam Problem. It originated on the news.admin.net-abuse.email newsgroup, I think, maybe twenty years ago? While one or two details have changed it’s still applicable to most of […]

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The Problem With Affiliates (2)

On Friday I mentioned spam coming from a BarkBox affiliate programme. The original email is here. It’s not terribly exciting, it’s rather typical spam of the sort sent by professional spammers. It’s validly DKIM and SPF authenticated, and DMARC-aligned. It includes invisible white-on-white padding text so that it doesn’t look like image-only spam to naive […]

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The Problem With Affiliates

If I see BarkBox I think Spam. That’s because, despite their marketing team effort, facebook and banner ad budget, the main place I see them advertised is via spam in my mailbox. It’s not even good spam. There’s quite a lot of it. Most of it looks much the same, other than the spammer randomizing […]

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Reading RFCs

We mention RFCs quite a lot, both explicitly (RFC 6376 is the specification for DKIM) and implicitly (the 822.From aka bounce address aka return path). And we have local copies of a bunch of them to make them easy to refer to (SMTP, MIME, Carrier Pigeons …). They use quite a lot of jargon and […]

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Minimal DMARC

The intent of DMARC is to cause emails to silently vanish. Ideally deploying DMARC would cause all malicious email that uses your domain in the From address, but which has absolutely nothing to with you to vanish, while still allowing all email you send, including mail that was sent through third parties or forwarded, to […]

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