Cold Email
Stand up SPF, DKIM, DMARC, and a dedicated sending domain before your first B2B cold outreach so messages reach inboxes instead of burning your main domain reputation.
Overview
Cold Email is an agent skill for the Launch phase that walks solo builders through cold-email deliverability—domain setup, SPF/DKIM/DMARC, infrastructure, and list quality—before worrying about outreach copy.
Install
npx skills add https://github.com/alirezarezvani/claude-skills --skill cold-emailWhat is this skill?
- Six-layer deliverability stack ordered from domain reputation down to engagement signals—fix problems bottom-up before o
- Dedicated sending domain patterns (subdomain, lookalike, get/try domains) with rules to never blast from primary company
- SPF, DKIM, and DMARC authentication as mandatory identity layer before scaling sends
- List quality, sending infrastructure ramp-up, and content spam signals called out as separate layers
- Guidance to put a real site or redirect and proper mailbox on the sending domain to avoid phishing appearance
- Deliverability modeled as six stacked layers from domain reputation through engagement signals
Adoption & trust: 575 installs on skills.sh; 17.5k GitHub stars; 2/3 security scanners passed (skills.sh audits).
What problem does it solve?
You want to send cold outreach but have not authenticated your domain or isolated send risk, so every blast could land in spam and poison email for your whole business.
Who is it for?
First-time B2B outbound from a solo SaaS or services shop that owns a domain but has never run a deliverability pre-flight.
Skip if: Teams on fully warmed outbound stacks with monitored reputation, or builders who only do inbound/SEO and will never send cold email.
When should I use this skill?
You are planning or sending cold email and deliverability, domain isolation, or SPF/DKIM/DMARC is not yet verified.
What do I get? / Deliverables
You leave with a dedicated sending domain plan, authentication layers aligned, and a bottom-up deliverability checklist so outbound can scale without sacrificing your primary domain.
- Dedicated sending domain and mailbox plan
- SPF/DKIM/DMARC alignment checklist
- Bottom-up deliverability remediation order
Recommended Skills
Journey fit
Cold outbound is how many solo builders acquire first customers after the product exists—canonical shelf is Launch because the motion is distribution, not product construction. Distribution covers non-inbound channels such as structured outbound email to prospects and partners.
How it compares
Infrastructure and reputation playbook for outbound email—not a sequence copywriter, CRM workflow, or MCP integration.
Common Questions / FAQ
Who is cold-email for?
Solo and indie builders doing B2B cold outreach who need domain, DNS, and sender-reputation basics before scaling sequences.
When should I use cold-email?
Use it in Launch (distribution) when you are about to send—or already sending—cold email and have not verified SPF/DKIM/DMARC, a dedicated sending domain, and list quality; also when deliverability drops and you need to debug from the stack bottom up.
Is cold-email safe to install?
It is advisory documentation for DNS and sending practices; review the Security Audits panel on this Prism page before installing any skill from the repo.
SKILL.md
READMESKILL.md - Cold Email
# Deliverability Guide A cold email that lands in spam is worse than no email at all — it damages your sender reputation for future sends. Get deliverability right before you worry about copy. --- ## The Deliverability Stack Email deliverability is a layer cake. Every layer has to be correct: ``` Domain reputation (is your domain trusted by inbox providers?) ↓ Authentication (SPF, DKIM, DMARC — are you who you say you are?) ↓ Sending infrastructure (IP reputation, sending limits, ramp-up) ↓ List quality (are you sending to real, active addresses?) ↓ Email content (does the content look like spam?) ↓ Engagement signals (opens, replies, not-spam clicks) ``` Fix problems from the bottom up. No point perfecting copy if your domain is blacklisted. --- ## Domain Setup ### Use a Dedicated Sending Domain Never send cold email from your primary company domain (`acme.com`). If your cold email domain gets flagged or blacklisted, you lose your main domain's email reputation. **Setup options:** - `mail.acme.com` — subdomain of main domain - `acme-hq.com` — separate domain with similar name - `getacme.com` / `tryacme.com` — common pattern for SaaS **Rules for the sending domain:** - Set up a proper website (even a simple redirect to main site) — bare domains look suspicious - Match the company name visually — unrelated domains look like phishing - Get a G Suite / Microsoft 365 mailbox on it — shared hosting email servers have worse reputation ### SPF Record SPF (Sender Policy Framework) tells receiving servers which IP addresses are allowed to send email from your domain. Without it, your emails look unauthenticated. **DNS TXT record:** ``` v=spf1 include:_spf.google.com ~all ``` Replace `_spf.google.com` with your sending provider's SPF include. Check your provider's documentation for the exact value (Google Workspace, SendGrid, Mailgun, etc. all have their own). **Important:** Only have ONE SPF record per domain. If you have multiple, they conflict and authentication fails. ### DKIM DKIM (DomainKeys Identified Mail) adds a cryptographic signature to your emails, proving they weren't tampered with in transit. Setup is done through your email provider — they give you a DNS TXT record to add. It looks like: ``` google._domainkey.yourdomain.com IN TXT "v=DKIM1; k=rsa; p=MIGfMA0..." ``` The public key in that record lets receiving servers verify your email's signature. ### DMARC DMARC ties SPF and DKIM together and tells receiving servers what to do when authentication fails. **Starter DMARC record (monitoring mode):** ``` _dmarc.yourdomain.com IN TXT "v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com" ``` `p=none` means monitor but don't block — good to start with. Once you've confirmed SPF and DKIM are working cleanly, move to `p=quarantine` or `p=reject`. ### Verify Everything Use **mail-tester.com**: send a test email to their address, then check your score. 9/10 or higher means your authentication is clean. Below 7/10 means something is broken. --- ## Domain Warmup A brand new domain has no sending reputation. Email providers don't trust it. If you start sending 200 emails/day on day one, you will be flagged. Warmup = building reputation gradually by sending low volumes and getting positive engagement. ### Warmup Schedule | Week | Emails/Day | Focus | |------|-----------|-------| | 1 | 5-10 | Real conversations only — send to colleagues, get replies | | 2 | 20-30 | Small cold outreach batches — highly targeted, good lists | | 3 | 40-60 | Expand slightly — maintain >30% open rate | | 4 | 80-100 | Normal volume — watch bounce and spam complaint rates | | 5+ | Up to 200 | Full volume — monitor daily | **Warning signs that warmup is failing:** - Open rate drops below 20% - Bounce rate above 3% - Spam complaint rate above 0.1% - Emails landing in Gmail Promotions tab **Manual warmup vs tools:** Tools like Lemwarm, Warmup Inbox,