Root cause of zero conversions since Jun 9 + the Gmail/Outlook block storm:
the send filter was '(email_verified IS TRUE OR result IN ...)'. The verifier
sets email_verified=TRUE optimistically for mx_unreachable (domain exists but
its mail server never answered the RCPT probe) — 438,163 such rows. Those HARD
BOUNCE on send, producing ~1,100 bounces/day (~47% rate) and blocklisting half
the 120k subscriber base, so real prospects never saw the offer.
Fix: key the send filter ONLY off email_verify_result, never the broken boolean.
Recovery mode (default): send only 'smtp_valid' to drive bounce rate to ~0 and
rebuild reputation; set CAMPAIGN_INCLUDE_CATCH_ALL=1 to re-add catch-all domains
once recovered. Mirrors the healthcare list-cleaning approach (HC bounces ~2-3%,
which proves the fix). Note: only ~3k smtp_valid unsent remain — list growth via
real-send bounce verification (separate burner domain) is the follow-up.