Tracking of opened emails are done using an embedded tracking image. When the image is loaded the opening of an email can be tracked. Because of this the image needs to be loaded, the tracking of opened emails is depending on the behavior of the email client, used by the user.
Some email clients, like the email client in iOS devices like iPhone, loads images when viewed in the email client. Other clients, like Microsoft Outlook, doesn’t load images by default, even when the email is viewed. Images are loaded when the user manually chooses to load images.
Notice that if a user replies to an email, clicks a link or posts a form, the email will be considered opened regardless if the tracking image has been loaded or not.
Important information about spam and anti virus filters
Some spam and anti virus filters analyze links in each email by accessing the link and analyzing the website to ensure that the website is secure. Since the link is unique in each email, this results in that each link will be considered as clicked. We recommend investigating the impact of your security functions, and if possible, add exceptions for the sender of the assessment, so that the statistics are not affected.
Is automatic loading of images good or bad?
As mentioned some clients load images automatically, which also makes them automatically load the tracking image. It's possile to implement a policy to load images automatically in Outlook. Holm Security doesn't recommend to implement such policy because the email will be considered opened even if the user haven't actually read the email. Anyway, the challenge here is that still many clients, like in iPhone, will load the tracking image regardless.