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Tag: Technical

Weird mail problems today? Clear your DNS cache!

A number of sources are reporting this morning that there was a problem with some domains in the .com zone yesterday. These problems caused the DNS records of these domains to become corrupted. The records are now fixed. Some of the domains, however, had long TTLs. If a recursive resolver pulled the corrupted records, it […]

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Post-mortem on the Spamhaus DOS

There’s been a ton of press over the last week on the denial of service attack on Spamhaus. A lot of it has been overly excited and exaggerated, probably in an effort to generate clicks and ad revenue at the relevant websites. But we’re starting to see the security and network experts talk about the […]

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More on the attack against Spamhaus and how you can help

While much of the attack against Spamhaus has been mitigated and their services and websites are currently up, the attack is still ongoing.  This is the biggest denial of service attack in history, with as much as 300 gigabits per second hitting Spamhaus servers and their upstream links. This traffic is so massive, that it’s […]

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You can't technical yourself out of delivery problems

In many cases these days, many more cases than a lot of senders want to admit, delivery problems at the big ISPs are a result of sending mail recipients just don’t care about. The reason your mail is going to bulk? It’s not because you have minor problems in your headers. It’s not because you […]

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The Physics of the Email Universe

We talk a lot about rules and best practices in email, but we’re mostly talking about “squishy” rules-of-thumb that are based on simplified models of how mail systems, spam filters, recipients, postmasters and blacklist operators behave. They’re the biology, ecology and sociology of the email ecosystem. There’s another set of rules we tend to only […]

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Who leaked my address, and when?

Providing tagged email addresses to vendors is fascinating, and at the same time disturbing. It lets me track what a particular email address is used for, but also to see where and when they’ve leaked to spammers. I’d really like to know who leaked an email address, and when. All my inbound mail is sorted […]

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Analysing a data breach – CheetahMail

I often find myself having to analyze volumes of email, looking for common factors, source addresses, URLs and so on as part of some “forensics” work, analyzing leaked emails or received spam for use as evidence in a case. For large volumes of mail where I might want to dig down in a lot of […]

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Character encoding

This morning, someone asked an interesting question. Last time I worked with the actual HTML design of emails (a long time ago), <head> was not really needed. Is this still true for the most part? Any reason why you still want to include <head> + meta, title tags in emails nowadays? There are several bits […]

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Defending against the hackers of 1995

Passwords are convenient for the end user, but it’s too easy to lose control of them. People share them with other people. People write them down, where they can be read. People send them in email, and that email is easily intercepted. People’s web browsers store the passwords, so they can log in automatically. Worst […]

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What is Two Factor Authentication?

Two factor authentication, or the snappy acronym 2FA, is something that you’re going to be hearing a lot about over the next year or so, both for use by ESP employees (in an attempt to reduce the risks of data theft) and by ESP customers (attempting to reduce the chance of an account being misused […]

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