A technical-and-list hygiene kit for operators whose open rates collapsed overnight.

Includes:

• SPF, DKIM, and DMARC setup checklist in plain language
• List-clean rules before the next send
• Warm-up schedule after a domain issue
• Complaint and bounce response playbook
• Test-send protocol across Gmail, Outlook, and Apple Mail

Not a copy system or segmentation playbook — this is how the mail actually arrives.