Will ARC become mandatory for intermediaries?

ARC (Authenticated Received Chain) may become mandatory for mail intermediaries like mailing lists and forwarding services. Currently optional, ARC solves authentication problems these services create.

As providers rely more heavily on authentication for filtering, the problems ARC solves become more acute. Mailing lists without ARC support will increasingly face delivery problems as authentication requirements tighten.

Industry pressure or explicit requirements could drive ARC adoption among intermediaries. The technical groundwork exists; adoption depends on incentives or mandates pushing implementation.