Tag: Technical

The secret to fixing delivery problems

There is a persistent belief among some senders that the technical part of sending email is the most important part of delivery. They think that by tweaking things around the edges, like changing their rate limiting and refining bounce handling, their email will magically end up in the inbox. This is a gross misunderstanding of […]


Analysing lead-gen spam

Yesterday I showed how major companies hire hard core spammers. Today I’m going to show you some of the technical details as to how I found that data. This is a fairly quick and shallow analysis, the sort of thing I’d typically do for a client to help them decide whether the case was worth […]


Which is better UTF-8 or ISO-?

Someone asked today on a mailing list whether they should be using UTF-8 or “ISO” encoding for sending email. What’s the best choice depends on some of the details of the situation, but here’s the answer I gave: UTF-8 will work for pretty much anything, as it’s just an 8 bit encoding scheme for Unicode […]


Troubleshooting the simple stuff

I was talking with one of my Barry pals recently and was treated to a rant regarding deliverability experts that can’t manage simple things. We’ve been having an ongoing conversation recently about the utterly stupid and annoying questions some senders ask. Last week, I was ranting about a delivery person asking what “5.7.1. Too many […]


Email is store and forward

Many of us are so used to email appearing instantaneous, we forget that the underlying protocol was never designed for instant messaging. When the SMTP protocol was originally proposed it was designed to support servers that may have had intermittent connectivity. The protocol allowed for email to be spooled to disk and then sent when […]

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What is an email address? (part two)

Yesterday I talked about the technical definitions of an email address. Eventually on Monday I’m going to talk about some useful day-to-day rules about email address acquisition and analysis, but first I’m going to take a detour into tagging or mailboxing email addresses. Tagging an email address is something the owner of an email address […]


What is an email address? (part one)

Given we deal with email addresses every day, dozens or thousands or millions of them, it seems a bit strange to ask what an email address is – but given some of the problems people have with the grubbier corners of address syntax it’s actually an interesting question. There are two real standards that define […]



Yesterday, on an ESPC call, Mike Adkins of AOL announced upcoming changes to the AOL reputation system. As part of these changes, AOL will be checking DKIM on the inbound. Best estimates are that this will be deployed in the first half of 2009, possibly in Q1. This is something AOL has been hinting at […]

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Ironport response

Last week I posted about a ESP that had a misconfiguration in their Ironport A60s that let spammers use the A60s to relay email to AOL. Earlier this week, Pat Peterson from Ironport approached me to talk about the problem and clarify what happened. Ironport has provided me with the following explanation. As part of […]

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ESP unwittingly used to send spam

Late last week I heard from someone at AOL they were seeing strange traffic from a major ESP, that looked like the ESP was an open relay. This morning I received an email from AOL detailing what happened as relayed by the ESP. IronPort Open Relay Vulnerability Systems Affected IronPort A60 running software version 2.5.4-005. […]


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