Hi,
i had the same problem with bulking.
Bulking is hardcoded but i did not found a solution to override this in a safe way.
Infos:
Because the module Names are hardcoded in the notify.py
split_contexts = (
plugin_name not in ["", "mail", "asciimail", "slack"] or
# params can be a list (e.g. for custom notificatios)
params.get("disable_multiplexing") or bulk)