Can you tell me some example programs where pasting it results in this small size. You say email but you dont say what email client, etc. I need to reproduce the problem before I can solve it.
What may be happening is that the default way to copy an image to the clipboard is to copy it as a bitmap, which does not have any DPI information. And when that is done, your email client is assuming its a small physical size image and displaying it as such.
But that when you copy the original image to the clipboard using some other tool, it's saving it to the clipboard in multiple formats, including some image formats that include dpi information which the email client can use.
But I'm still curious about how you are pasting the image into your email client when you do and do not use CHS.
When you paste the image into your email client not using CHS, and it looks fine, you are using CTRL+V to paste it into your email, and it's pasting it directly right, not as an explicit file attachment.
And when you paste using CHS, you are using CTRL+V again?