Over the last weekend, I made a change to the List-Id header, adding the group's id as a prefix. The idea is that I'd be able to use this to help identify messages sent via the FBL mechanism where we receive spam reports (sometimes email providers will counter-productively obscure identifying information in these messages). This change was to be announced in tomorrow night's #changelog, as I didn't think it was a big deal. I have just now rolled back this change, for two reasons. 1) It turns out I don't really need it to identify FBL messages, and more importantly 2) many more people than I thought use the LIst-Id header to filter email, and the change broke those filters.
