iOS mail signature photo
On iOS 16.4, how to successfully add a small photo to my email signature? It works fine on Macos. I have read 10 websites, including LifeWire, with instructions to add a small photo on Macos > Apple Mail > draft, then copy photo into email signature, but it fails everytime. It says <photoname.jpg>, or it has a empty rectagle. The photo can be any size, it can be 9kb 30x30, or 15kb, 320x320, it does not matter the resolution or file size, they all fail. What am I doing wrong? Thank you.
iPhone XR, iOS 16