How to force TinyMCE Editor to use only external Link

Hi
I try to edit an e-Mail Text in TinyMCE Editor. This text has a link pointing to my SC-Application. Now TinyMCE is too smart, replaces all the time my link https://www.example.com with “…/” because the Editor runs also under https://www.example.com.
How can i force TinyMCE not to use internal links. I found this here: https://stackoverflow.com/questions/2492452/problem-with-insert-update-links-with-tinymce

Thank’s for your suggestions how to solve this in SC.
Best regards
Steve