If you've stopped receiving email alerts in your inbox then there are a number of things you can try:
1) Check that the Email alerts option is enabled in your Mailtrack settings. If it is disabled, re-enable it and save your settings then send a test email to see if you receive an email alert when it is opened.
2) Check to see if your most recent sent emails have been tracked and opened. You won't receive an email alert for a particular email unless there are two green check marks next to it in your sent mail folder indicating that it has been opened. If you can only see grey check marks next to your recently sent emails, however, then there may be an issue with Mailtrack's installation on your web browser. Reinstalling Mailtrack on your browser will normally fix this. Instructions explaining how to reinstall Mailtrack on your browser can be found here.
3) Check to see if email alerts appear when you click to view 'All Mail' in Gmail. If email alerts aren't arriving in your inbox but you can see them when you click on 'All Mail' then you may need to set up a filter in Gmail in order to make sure that emails sent from email@example.com are delivered to your inbox. This post in the Gmail Help Forum provides instructions on how to do this.
4) Test with a different email account. If you are receiving email alerts when sending tracked emails from a different email account on the same device and with the same internet connection, then the issue with the email alerts is most likely being caused by the configuration of your email account. Check to make sure that firstname.lastname@example.org isn't listed in your Gmail settings as being blocked. If you are using Mailtrack with a company email account also speak with your company's IT department about whitelisting mailtrack.io so that the email alerts aren't filtered by your company's mail server.