Additionally to this tutorial on interacting with Discourse via email, this topic is for people wishing to create new GIMP-related topics by email (This thread was itself originally started by email as a proof-of-concept, though I edited it further later on):
Your account needs to have sufficient trust level by having contributed several topics and messages through the web GUI for this to be possible (“level 1” required, though we are not sure what it entails; but basically it means you can’t just create a new account and directly expect being able to create new topics by email).
To start a new thread, send an email to a category of this Discourse on the
<category>@discourse.gnome.orgemail, though not all categories work. At the very least
community@email is known to work.
The email subject will need to contain
[GIMP]. This will automatically tag the thread for our section.
Thanks to @averi for the help and special configuration making this possible!