I use gmail. I noticed forum update emails arriving in my "primary" inbox, rather than the forums tab. I think this stated late last night and has continued this morning.
On closer inspection, up until about 2100 last night (Monday 17), notification emails were coming from "forums [at] geekzone.co.nz".
From then on, emails seem to be coming from "forums[some sequential number] [at]geekzone.co.nz".
This seems to have broken grouping the email threads (i.e. all updates from the same forum being grouped in one). Because each sender is "unique" I can't set a rule to move everything to the forums tab.
Anyone else getting this or is it something I've done?