I have no idea (didn't find out from a quick browse through the site), but the first thing that came to mind was an image in the mail, pointing to a server that slowly trickles a response without ever finishing so it can measure how long the other end is listening.

I guess that could work if mail clients don't have timeouts for images.

I still can't imagine how they would detect deletion though.

They're just calling "viewed for <x seconds" a deletion, it seems...

A timeout would possibly be after an engagement time that means "probably read the whole thing", e.g. 60 seconds.

Pretty genius idea but easy to replicate by the big boys..

Big boys move slowly. Plus, what isn't "easy to replicate?" aside from network effects.

I worked at an ESP (Email Service Provider) a few years back. It may not be anymore, but it was a crazy environment back then of everyone trying to compete.

The major issue with this is going to be scaling it, with large ESP's doing 50-100 million messages a day, and 20-30% of those being opened, that's a lot of processes. This solution will probably be effective, mostly because it's going to a much smaller segment.

1. In the HTML email put

    <img src="http://myserver/invisible.gif">

2. Serve up http://myserver/invisible.gif with a process that trickles down an endless GIF image a few bytes at a time.

3. When the connection to the endless GIF dies, call that the "reading" time.

4. If a "reading" time is under some threshold call it "deleted".

That's how I did it a few years ago anyway.

That's a neat trick. After hearing about Mirapoint, I built a simple proof of concept that uses time-delayed redirects to gauge how long a user has attempted to load an image:

https://github.com/derwiki/redirect_tracker

Like most email metrics, it's lacking -- but this is still -a little- more information, and that goes a long way in email marketing.

i never load images automatically in my emails, and I bet a lot of other people do that too

If the sender is ReturnPath certified, Hotmail and Yahoo! automatically load images. Those two providers account for a large portion of email on the internet, so there's definitely value in this product.

We have a special tracking code that figures it out over the email clients' use of HTTP and with some fancy server-side node/mongodb stuff.

Maybe a throttled node.js response on an img on a large image file? edit: Oops I see that staunch beat me to it.

It's still bullshit. Most email clients don't display images by default. The notion that email reading behavior can be tracked with anything resembling reliability is a blatant lie.

Bullshit. There's not a single major client that executes code from emails.

You might be able to have some <img> link back to your server, but even those are blocked by default.

Are images blocked on hotmail, yahoo, etc. too now? I've only used gmail for the past 5+ years.

Either way though, it wouldn't really produce a random sample, though maybe it would allow somewhat meaningful comparisons between separate email campaigns even if the absolute numbers aren't too meaningful.

Yeah, all of them block images for emails that come from new contacts.

They aren't blocked by default in all clients. Check your mom's iPhone, it loads images by default.

If that's true, it's very dangerous. Imagine somebody finds an iphone image vulnerability, a virus based on it will spread across the whole world in a couple of hours.