When all emails have been sent, Mailmeteor generates a tracking report with emails opened and clicked. Also, you can open tracking report from Add-ons menu > Mailmeteor > Tracking report.
A merge status will be created after sending email in your spreadsheet. The tracking report is a sidebar on the right summarizing information about emails clicked and opened.
In the merge status column, you can get several states:
In the tracking report, you can find open and click rates:
If you've got an error message, check all error messages and how to solve them.
You can access tracking stats days or months later after your campaign was sent without problem.
Mailmeteor tracks opens and clicks in real-time. The tracking system implemented by Mailmeteor is industry standard. It works by adding a small image (called a 1x1 pixel) on the bottom of each email you send. Every time someone opens your email, it downloads that small image and Mailmeteor records that opening in its database.
Some email providers are downloading that pixel before a user opens the mail. They don't do it 100% of the time, which is why some emails are marked as opened immediately after sending and some not.
Other email providers are blocking images by default. Which means that sometimes your email is marked as sent only, while it has been opened. Email providers are doing so for privacy reasons - with the idea to block as much as they can all tracking technologies. With this in mind, we consider that the tracking system is more a hint.