In theory I could, but the problem is actually hidden a few layers deep within the software I am trying to run.

The actual problem seems to be caused within the package nodemailer when trying to send an email using SMTP. Nodemailer is used by the mailing list tool mailtrain, which is running inside a docker container.

I could of course now dive into the source code of nodemailer, try to isolate the line which is causing the problem, then extract & fix the corresponding file and mount it as an overlay into the docker container, but that really seems like an overly complex solution :/