Copying images from Xnview MP to email clients

[crimle]

- Open an image with Xnview MP
- Copy it to the clipboard by pressing [Ctrl]+[Shift]+[c]

1. Open Thunderbird
- Open a new email
- Insert the image from the clipboard to the email message by pressing [Ctrl]+[v]
→ This adds a thin grey line above the image.
→ Inserting the image without Xnview MP being involved, the image has no grey line above
→ See screenshot

2. Open Outlook
- Open a new email
- Insert the image from the clipboard to the email message by pressing [Ctrl]+[v]
→ The image has horizontal stripes and does look really bad
→ See screenshot

How can I prevent this? Is this a bug with Xnview MP? Or is this issue related to my computer's clipboard?

Thank you and kind regards
Chris

[xnview]

it seems that your image is 32bits, and client doesnt support it