Mailtrack is one of the most reliable and accurate email tracking solutions in the market, our reliability is much higher than our competitors and we keep improving it, however, the tracking technology has some limitations.
There are two main causes of inaccuracy:
1) If you send emails to yourself Mailtrack can't work well, so please, don't test Mailtrack by sending an email to yourself, but to someone else and please don't use the same computer to send the email with Mailtrack and to open the email.
2) In some cases, your email has been opened, but Mailtrack says it is not opened. This can happen to a small percentage of emails sent with Mailtrack.
The main reason is that some email clients (e.g. Outlook) might block images from showing on emails by default, and this is a limiting feature for email marketing software because we track emails by including a small pixel in your message. This is a limitation shared by all email marketing tools.
The good news, though, is that this default blocking is becoming a thing of the past. In fact, Gmail itself changed its policy at the end of 2013 and since then opens all images by default, increasing considerably our efficiency.