Sure, we can add an option for this. Thanks for your feedback! :)

@MocioF I think we could make this the default option, like we always try to fetch the featured image, if it's not then we could look for the first image in the post and then fallback to the website icon. What do you think?

In my commit I checked the "send featured image or..." as default settings.
Not sure I understand the request

Yes, and maybe we could remove the option and treat it as if the option is always "checked".

I can send a PR to simplify things and fix a bug I'm facing with the Body of the notification which is always empty when the Custom check is unchecked.

This has been released in v1.3.1