So, if the image you want to put into your email is not hosted somewhere, what’s the best way to go about this, ensuring compatibility?
You can base64-encode the image file. It’s super-jank, but it works, even in Outlook.
Example: https://www.base64-image.de/tutorial
Web development in North Germany, for a small agency. We mainly work with WordPress and Typo3, which is used by the government, clinics and other “bigger” institutions a lot here.
I actually like PHP (most people seem to hate it :D), so it’s a good job.