Your software
My Mautic version is: 3.1.1
My PHP version is: 7.3.17
My Database type and version is: MySQL 5.7

Don’t know if it’s a “problem” or just a general question.

How can one give Content-IDs to attachments and use them in emails?
Basically, I want to attach images inside an email so that they are not just externally linked.