February 18, 2026
10 Mistakes Killing Your Cold Email Campaigns (And Fixes)
Discover the 10 most common cold email mistakes that destroy deliverability and reply rates. Practical fixes for each one to improve your campaigns.
Why your campaigns aren't working
You've set up your cold email tool, imported your list, written your sequence — but results are terrible. Low open rates, zero replies, maybe even spam complaints. Here are the 10 mistakes killing your campaigns and how to fix each one.
Mistake 1: Sending from your main domain
The problem: If your cold emails get flagged as spam, your main domain reputation tanks. Your regular business emails start going to spam too.
The fix: Buy a separate domain for outreach. Use yourbrand-outreach.com instead of yourbrand.com. Costs $10/year and protects your business.
Mistake 2: Skipping warm-up
The problem: Sending 100 emails from a brand-new mailbox on day one guarantees spam placement.
The fix: Warm up for 2-4 weeks. Start with 5 emails/day, increase by 5-10 every few days. Be patient — this investment pays off.
Mistake 3: Writing emails that are too long
The problem: Cold emails over 200 words see dramatically lower reply rates. Nobody reads a wall of text from a stranger.
The fix: Keep it to 3-5 sentences, under 150 words. Structure: Hook → Value → CTA.
Mistake 4: No personalization
The problem: "Dear Sir/Madam" or even just "Hi {first_name}" isn't personalization. Spam filters detect generic templates.
The fix: Reference something specific — their company, recent news, their role, a piece of content they published. AI can help generate personalized openers at scale.
Mistake 5: Too many links
The problem: Multiple links in a cold email is a major spam trigger. Calendar links, website links, case study links — each one hurts deliverability.
The fix: Zero or one link maximum. If you must include a link, make it your signature link. Save the case study for the reply.
Mistake 6: Using spam trigger words
The problem: Words like "free", "guarantee", "limited offer", "click here", "act now" trigger spam filters.
The fix: Write naturally. Read your email out loud — if it sounds like an ad, rewrite it. Use a deliverability score tool to catch trigger words before sending.
Mistake 7: No unsubscribe option
The problem: Beyond being legally required (CAN-SPAM, GDPR), missing unsubscribe links mean frustrated recipients mark you as spam instead. Spam reports destroy your reputation.
The fix: Include a simple unsubscribe link in every email. HeraMail adds this automatically.
Mistake 8: Bad list quality
The problem: Purchased lists, scraped emails, outdated contacts — high bounce rates kill your sender reputation fast.
The fix: Verify emails before importing. Aim for <2% bounce rate. Remove hard bounces immediately. Clean your list monthly.
Mistake 9: Sending everything at once
The problem: Blasting 500 emails at 9:00 AM from one mailbox looks like spam to email providers.
The fix: Spread sends throughout the day. Use multiple mailboxes with rotation. Keep volume below 50 per mailbox per day.
Mistake 10: Not checking deliverability before sending
The problem: Most people find out their emails are in spam after the campaign is done. Wasted time, wasted contacts.
The fix: Check a deliverability score on every email before sending. Fix flagged issues. Only send emails scoring 80+.
Quick diagnostic checklist
| Symptom | Likely cause | Fix |
|---|---|---|
| Low open rates (<20%) | Spam folder | Check authentication, warm up, reduce volume |
| Opens but no replies | Bad copy | Shorten email, improve CTA, add personalization |
| High bounce rate (>3%) | Bad list | Verify emails, clean list |
| Spam complaints | No unsub + bad targeting | Add unsubscribe, improve targeting |
| Account suspended | Volume too high | Reduce volume, add rotation |
Fix your campaigns — HeraMail scores every email before sending: heramail.io