What broke, and how do we find it?
Deliverability failures cluster around four causes: missing or misaligned authentication, complaint rates over Gmail's thresholds, sustained sends to unengaged profiles, and list-quality problems like purchased addresses or spam traps. Week one is diagnosis: DNS records, Google Postmaster Tools reputation history, complaint trends, and a GlockApps seed baseline across Gmail, Outlook, and Yahoo.
What are the fixes?
- Authentication. SPF, DKIM, and DMARC set up and aligned on your sending domain. Required for bulk senders under Google's sender guidelines, and the first thing we verify.
- One-click unsubscribe. RFC 8058 list-unsubscribe headers, so recipients opt out instead of hitting "report spam." Complaints count against you; unsubscribes do not.
- Engagement-based sending. Sends restricted to engaged segments from the audience map during recovery, then widened carefully as reputation rebuilds.
- Sunset policy. A standing rule that retires silent profiles before they poison your metrics again.
What does recovery look like in numbers?
The membership app's seven-week arc: 29% of profiles suppressed in weeks two through four, complaint rate down from 0.36% to 0.05%, Gmail placement from 78% to 98%, and the cancel-save flow's click rate up from 3.4% to 6.1% once it was reaching inboxes again. The complete timeline is in the fitness app write-up.
After recovery, monitoring stays on: monthly GlockApps seeds, Postmaster reputation checks, and complaint-rate alerts at 0.1%, well under Google's 0.3% enforcement line. Deliverability is a maintenance discipline, and it is included in every Growth Retainer.