Symptoms#
- Messages landing in spam despite previously good placement
- Bounces mentioning policy, authentication, or reputation
- Provider dashboards showing a drop in reputation or authentication pass rate
Diagnosis steps#
- Confirm the configuration is live: query DNS from an external resolver and check the sending platform's settings page.
- Send to a seed mailbox and read the full headers, especially Authentication-Results.
- Compare the domains in From, Return-Path, and DKIM d= for alignment.
- Check provider dashboards (Google Postmaster Tools, Microsoft SNDS) for reputation and error rates.
- Review recent changes: new vendors, DNS edits, list imports, volume spikes.
Likely causes#
- Continuing after a negative reply.
- Identical cadence for every contact regardless of engagement.
Fix and re-verify#
- Plan 3 to 5 steps over 2 to 3 weeks; diminishing returns set in after step 5.
- Give each step a distinct angle rather than 'just bumping this'.
- Stop the sequence automatically on reply, bounce, or unsubscribe.
- Thread follow-ups as replies for context, but vary subject lines when starting new angles.
- Review reply sentiment weekly and adjust.
Frequently asked questions#
How many follow-ups should a cold sequence have?
Three to five. Most positive replies come by step three; beyond five, complaints rise.