Documents the 2026-06-18 reputation incident (snowshoe -> Gmail domain-rep
blocks, RBLs all clean), the single-IP-per-stream consolidation, and
fill-in-the-blanks setup steps for Google Postmaster Tools, Microsoft SNDS/JMRP,
and Yahoo CFL (all require owner account login + HE.net DNS). Plus ongoing
hygiene + how to re-expand IPs once reputation recovers.
