I don't know how they do it, but it can be done by embedding an image (say a 1x1 pixel transparent) into the message. Each time the message is opened, the image is fetched from the server. Count the hits.
Modified version. Same as above, but generate the image with php. "Tag" each image/url with the user's id number: <img src="http://example.com/tracker.php?id=123456789" />. Observe the hits.
These are older methods. Mail tracking may be different now. These are easily worked around in modern email clients, by the way. Use Outlook or Gmail lately? This is part of the reason all images are blocked by default. There are valid privacy concerns.
Very few e-mail applications or services support read receipts...
Still, if someone is using Outlook, they may not be very savvy anyway, so they may be tracked via read receipt just as easily as by image. Among those who think they're savvy (like me), they will disable the junk in Outlook but will gladly accept HTML email so they can see pictures of the nice, shiny weekly sale items.
yeah. Thats the true "above board" method shall we say of confirming it. You can use the image method, although this isnt guaranteed to work either since services like gmail download the images before the account user receives it, and caches it to show them, so it again isn't 100%. Also clients such as Thunderbird (mozillas free alternative to outlook) by default will block images and only show them upon the users request (by clicking a display images button)
So, does that mean that when aweber shows that you only
got a 20% opened rate, it could really be a lot higher, it is just that
people are not allowing images ?
In fact, if Google is opening and caching the images for their gmail clients.
the opposite would be true - all gmail mails would appear to get opened and read ) cos Google is doing it) when really they might not be.
As far as I can see the only methods of checking on
opening/reading of sent emails are not reliable.
So the point is, if this is true then
there is not really a way of knowing if
your emails are being read, or any way of
getting good stats.
I guess that the big companies may have run
some tests and can tell that as a general rule
if they monitor that 20 % are opened then that
means that the real figure is going to be more
like 45% ( or 15% which ever way it works out)