--- name: deliverability-audit description: "Use this skill when cold emails land in spam or reply rates suddenly drop: \"audit my email deliverability\", \"why are my emails going to spam\", \"check my sending setup\", \"open and reply rates fell off a cliff\". Checks domain setup (SPF, DKIM, DMARC, tracking domain), sending volume and patterns, bounce and complaint rates, list quality, content risks and inbox placement, ranks the problems by impact, and produces a fix plan with a recovery timeline." license: MIT metadata: title: Deliverability audit category: deliverability tags: "RevOps, SDR, Founders, Agencies" author: prosyo version: "1.0.0" keywords: "cold email deliverability audit, emails going to spam fix, email deliverability checklist, claude deliverability skill, inbox placement" inputs: "Sending domains and mailboxes, DNS records, Campaign metrics, Sample emails" outputs: "Ranked problems, Fix plan, Recovery timeline, Monitoring checklist" --- Use this when results drop and the copy has not changed. Most "the campaign stopped working" problems are deliverability problems: the emails are not being seen. ## Inputs - Sending domains and the number of mailboxes on each. - DNS records (SPF, DKIM, DMARC, MX) or permission to look them up. - Metrics per mailbox: volume per day, bounce rate, reply rate, spam complaints, over the last 30-60 days. - Two or three sample emails as sent. ## The play ### 1. Check authentication SPF, DKIM and DMARC must exist, align with the From domain, and pass. Large mailbox providers require all three for bulk senders and reject or junk unauthenticated mail. Read [references/audit-checklist.md](references/audit-checklist.md) for the full checklist and what each failure looks like. ### 2. Check the domain strategy - Cold email from the primary company domain risks the domain that carries invoices and customer mail. Use separate, aged sending domains that redirect to the main site. - Each sending domain has 2-5 mailboxes, not 20. - A custom tracking domain, or no open and click tracking at all for cold outreach. ### 3. Check volume and pattern - Per mailbox: 30-50 cold emails a day after warm-up is a common safe range. - Sending spread through the working day, not in one burst. - Sudden jumps in volume (doubling overnight) are a common trigger for filtering. ### 4. Check list quality Bounce rate over 2-3% means a list problem. Spam complaints over 0.1% (one in a thousand) are a red flag; 0.3% is the threshold large providers warn about. Old lists, purchased lists and catch-all-heavy lists are usual causes. ### 5. Check content Links (especially link shorteners), images, attachments, tracking pixels, spam-pattern words and heavy HTML all add risk. Cold email should be plain text-looking with zero or one link. ### 6. Test placement Send to a seed set of test inboxes across providers, or ask friendly contacts to check folders. Separate "inbox", "promotions or other" and "spam". ### 7. Rank and fix Order fixes by impact: authentication failures and blacklisting first, then list quality, then volume, then content. ## Output format ``` Verdict: healthy / at risk / damaged Problems (ranked): Recovery plan: Monitor weekly: bounce %, complaint %, reply rate per mailbox, placement test ``` ## What good looks like - Diagnosis by mailbox and domain, not just campaign averages; one bad mailbox can hide inside a healthy average. - The fix plan pauses damaged mailboxes rather than pushing more volume through them. - The common mistake is rewriting copy for weeks while the real cause is a missing DMARC record or a 6% bounce rate. ## Rules - MUST check authentication before content. - MUST recommend pausing any mailbox with bounces over 5% or complaints over 0.3%. - NEVER recommend tactics that disguise the sender or evade provider filters (hidden text, misleading headers, rotating look-alike domains to dodge complaints). - NEVER change DNS records without the user's approval. ## Example prompts - "Our reply rate went from 4% to 0.5% in two weeks. Audit our deliverability." - "Here are our DNS records and per-mailbox stats. What's wrong?" - "Build a deliverability checklist we run before every campaign." --- # Deliverability audit checklist ## Authentication | Check | Pass | Common failure | | --- | --- | --- | | SPF record exists | One TXT record starting `v=spf1` | Two SPF records (invalid), or missing | | SPF lookups | 10 DNS lookups or fewer | Too many includes → permerror | | SPF covers the sender | Sending service included | Mail sent by a tool not listed | | DKIM | Signing enabled, key published, passes | Key published but signing not turned on | | DMARC | `v=DMARC1` record at `_dmarc.domain` | Missing, or invalid syntax | | Alignment | From domain aligns with SPF or DKIM domain | Sending service signs with its own domain | | Reverse DNS / sending infrastructure | Handled by the mailbox provider | Self-hosted servers without PTR | ## Domain and mailbox setup - Sending domains separate from the primary domain for cold volume. - Domains older than 30 days before cold sending; warmed for 2-4 weeks. - 2-5 mailboxes per domain. - Real names on mailboxes, profile photos, a signature with company details. - Sending domain redirects to the main website. - Custom tracking domain if tracking is used. ## Metrics thresholds (per mailbox, 7-day window) | Metric | Healthy | Warning | Stop | | --- | --- | --- | --- | | Bounce rate | < 2% | 2-5% | > 5% | | Spam complaints | < 0.1% | 0.1-0.3% | > 0.3% | | Reply rate | > 3% | 1-3% | < 1% sustained (check placement) | | Daily volume | Within plan | +50% jump | Doubling overnight | ## Content risks - More than one link, link shorteners, links to new or low-reputation domains. - Images, attachments, heavy HTML templates. - Open tracking pixel on cold email. - Spam-pattern words, all caps, many exclamation marks. - Identical copy to thousands of recipients (use variation). ## Recovery timeline for a damaged mailbox | Week | Action | | --- | --- | | 1 | Pause cold sending; fix authentication and list issues; keep warm-up running | | 2 | Resume at 10-15 cold emails a day to the best-fit, verified contacts | | 3 | 20-25 a day if bounces < 2% and no complaints | | 4+ | Back to normal volume if placement tests show inbox | If a domain is listed on major blocklists or placement stays in spam after four weeks, retire it and move volume to healthy domains gradually.