What are you using for email? There should be an option - like in Outlook - to 'always display images'. People turn it off either because of security fears, or to save bandwidth. In gmail, the default is to not download images, but it gives you the option on an email-by-email basis to show images in an email. The web address you're seeing is the address where the image in question is hosted (images are rarely embedded in emails as such any more).
OnePlus 5T review: Hands-on