Extract attachment, delete it from the mail and replace with link to the file - like it used to be in AE original?

AFAIK, this was implemented in the "own" routines from the original addon. These routines have been removed because of incompatiblity. Thunderbird 68 has implemented in itself the requested / missing feature for deleted attachments from single messages only. To get this working, when deleting attachments with AEC from multiple messages I need a litle code change in Thunderbird itself:

https://bugzilla.mozilla.org/show_bug.cgi?id=1578801

Quote from tomattac

Is there something we could do to make this happen? Suggest it somewhere or support an ongoing request?

Best solution would be to integrate mass detachment in Thunderbird itself. Probably this is necessary for Thunderbird 78+ because of reduced addon possibilities with Web-/MailExtensions: https://bugzilla.mozilla.org/show_bug.cgi?id=92146

To get it working in Thunderbird 68 with the AEC addon, we need the code patch: https://bugzilla.mozilla.org/show_bug.cgi?id=1578801

To get it working in Thunderbird 78+ with an addon we need a API: https://bugzilla.mozilla.org/show_bug.cgi?id=1522828

I'm not a software engineer, so I can't provide the relevant code / patches. The best solution would be to provide a complete code patch to integrate the basic functions in Thunderbird 68+ / 78+ itself.