I set a linked image 1x1 in HTML email and send it to a recipient for tracking open (if get image then email is opened). It works, but when I send an email, Gmail user just open their inbox (Not my email yet), then has a request to my server to get an image. So I don't track exactly this email is opened. Is there any way to fix this error? Here's my code:
<body>
<img height=1 width=1 src="https://example.com/email/v?u=123&aid=sds36gf3rik" style = "display:none" />
</body>
Many thank.