Hi,

If I send patches to guix-patches@gnu.org, everything works as
intended. However if I send them to guix-patches@debbugs.gnu.org, I can
wait days and I get no confirmation at all.

This second address was found in the following command inside the Guix
devel manual:
> $ git send-email outgoing/0000-cover-letter.patch -a \
> --to=guix-patches@debbugs.gnu.org \
> [...]

It's in the "Multiple Patches" subsection of the "Sending a patch
Serie" section of "Submitting Patches".

Denis.