Hm, good idea! Could see this being quite useful, reducing email size and db size over time.
Did some tests to check:
No data in the Network responses that contain the URL.
Copy link address from ?? search menu, outputs FQDN.
(link address from empty ?? search outputs ticket zoom article)
Copy image address from ?? added content, no URL, it’s Base64.
I guess the only way for now is to see if there’s an option in the API call to change the code and output the URL instead. However, that sounds very risky and you absolutely shouldn’t 
Make a Feature request instead, i would for sure upvote this!
Hopefully someone else in the community here might know a trick or two on how to achieve this.