BLOG

Category: Technical

Apple MPP reporting and geolocation

A while back I wrote about Apple Mail Privacy Protection, what it does and how it works. Since MPP was first announced I’d assumed that it would be built on the same infrastructure as iCloud Private Relay, Apple’s VPN product, but hadn’t seen anything from Apple to explicitly connect the two and didn’t have access […]

2 Comments

Apple MPP

You’ve probably heard about Apple Mail Privacy Protection. Email marketing chat has been all a-twitter about it since it was announced in June. Skipping over all the “Openpocalypse” panic, what is it and what does it do? Image Loads It’s all about images in email and how they’re loaded (particularly invisible one pixel images that […]

3 Comments

The OSI Seven Layer Model

In the 1970s, while the early drafts of the Internet were being developed, a competing model for networking was being put together by the ISO (International Organization for Standardization). The OSI (Open Systems Interconnection) Model broke the work needed to implement a distributed network service into seven separate layers of abstraction, from the physical infrastructure […]

No Comments

Authentication

Some notes on some of the different protocols used for authentication and authentication-adjacent things in email. Some of this is oral history, and some of it may be contradicted by later or more public historical revision. SPF Associates an email with a domain that takes responsibility for it. Originally Sender Permitted From, now Sender Policy […]

1 Comment

Link tracking redirectors 2

It’s not too difficult to build your own link redirector, perhaps a few hours work for a basic implementation me, yesterday Yesterday I suggested that link tracking wasn’t too complex, but didn’t really have anything to back the claim up. And nobody trusts developer time estimates. So I cranked DEF CON Radio and wrote a […]

1 Comment

Link tracking redirectors

Almost every bulk mail sent includes some sort of instrumentation to track which users click on which links and when. That’s usually done by the ESP rewriting links in the content so they point at the ESP’s tracking server, and include information about the customer, campaign and recipient. The recipient clicks on the link in […]

No Comments

Gradual DMARC Rollout

Over on twitter Alwin de Bruin corrected me on an aspect of DMARC soft rollout I’d entirely forgotten about. It’s useful, so I thought I’d write a quick post about it. If you have a large mail stream and you want to avoid the Scary Red Flag Day when you turn on DMARC p=reject enforcement […]

2 Comments

Why do my URLs have two dots?

You take a turn, I take a turn At the SMTP level email is very much a simple line-by-line text based protocol. The client sends a command on a single line, the server responds with one or more lines (the last one marked by having a space in the fourth column), and then the client […]

1 Comment

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 […]

1 Comment

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 […]

1 Comment

Recent Comments

Archives