Google Domains blocking all Gitbook URLS: post-mortem 6 years ago
Do you use SPF and DMARC for your domain? You could have received instant reports to take actions sooner.
[ my public key: https://keybase.io/azizur; my proof: https://keybase.io/azizur/sigs/NNecQqyeYTxECtb9KP_KI6rJ9wM3hCmDeHUyuEQC5RE ]