12 critical mistakes that kill your cold email deliverability — and exactly how to fix each one.
Check off each item as you complete it. Complete all 12 and your emails will hit the inbox.
These 3 records determine whether your emails even have a chance of landing in inbox.
Add v=spf1 include:_spf.yourdomain.com ~all to your DNS. This tells receiving servers your mail server is authorized to send for your domain.
Tip: If using Google Workspace, use include:_spf.google.com
Generate a DKIM key in your email provider (Gmail/Outlook) and add the TXT record to your DNS. This cryptographically signs your emails so servers can verify they came from you.
Add v=DMARC1; p=quarantine; rua=mailto:your@email.com to your DNS. Start with "quarantine" (not "reject") for 30 days, then harden once warmed.
Skipping warmup is the #1 reason new domains get flagged. Follow this ramp-up or pay the spam consequences.
Use this domain for genuine conversations only. Reply to emails. Move threads to inbox. Do NOT send cold outreach during this phase — just warm the domain.
Mix warmup emails with light cold outreach. Monitor open rates. If opens drop below 20%, slow down.
If inbox placement is clean (>20% opens, zero spam complaints), you're ready to scale. Never jump straight to 500+/day — that's how domains get burned.
Services like Instant Warmup, Warmbox, or Lemwarm (free with Lemlist) automatically reply to your emails using a network of inboxes. This simulates real engagement and builds domain reputation faster. Budget: $0–$20/month.
Your email body can trigger spam filters even when everything else is perfect. Avoid these at all costs.
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Rule: If it sounds like a used car ad, it belongs in spam.
HTML emails with embedded images are spam filter magnets for cold outreach. Plain text emails (like you're emailing a friend) have the highest deliverability. Save images for follow-up emails only.
Generic subjects like "Quick question about [Company]" get flagged. Personalized: "Saw your post about [topic] — [Company] idea" gets opened. Use the prospect's name, a recent post, their company product, or a mutual connection.
How you send matters as much as what you send. These rules keep you off blacklists.
The safe ceiling for most new domains is 150–200 emails/day. Beyond that, spam complaint rates rise sharply. If you need more volume, add more domains — don't push one domain harder.
4+ follow-ups feel harassment. Space them 3–5 days apart. Stop after 3. If they haven't replied, they're not going to — move on and protect your sender reputation.
"From: Sarah at AcmeCo" is a red flag. "From: Sarah" is personal. Bonus: use your first name only, with your company in the subject line instead.
Spam filters weigh real contact info heavily. A phone number, LinkedIn URL, or physical address (even fake) signals legitimacy. Keep it simple: name, title, phone.
GlockApps ($25/month) tests your email against 20+ spam filters before you send. It tells you exactly which spam tests your email fails and why. This is the difference between "100% inbox" on your tool's dashboard and reality.
This checklist fixes your deliverability. The Cold Email Machine kit automates everything else — lead finding, AI personalization, follow-ups, and Telegram replies. One payment. Yours forever.