If your cold emails are getting zero replies, chances are Gmail’s AI is quietly deleting them. It’s not just about what you send—it’s about how you send it.

After learning the hard way, we’ve developed a system focused entirely on deliverability. Below are the 11 key signals we religiously monitor to ensure our emails land in the inbox and not in the spam folder.

1️⃣ Use a Dedicated SMTP on VPS

Forget shared tools.

We set up Postfix on a private VPS with a dedicated IP.

This ensures:

✅ Gmail sees a clean, consistent sender

✅ No third-party tool fingerprints

📈 Inbox placement skyrocketed

2️⃣ Advanced DNS Setup

SPF, DKIM, and DMARC are just the basics.

We went further by implementing:

🔁 PTR Records (Reverse DNS)

🔄 FCrDNS (Forward-Confirmed Reverse DNS)

These prove your IP belongs to your domain. Gmail loves this level of authenticity.

3️⃣ Manual Warm-Up + Slow Scaling

We don’t rush.

We went further by implementing:

Started sending 5–10 plain-text emails per day, with:

📨 No links

🧾 No HTML

👤 Only real human messages

Once reply rates stayed consistent, we scaled slowly over 45 days.

4️⃣ Mimic Human-Like Rate-Limiting and Greylisting

To appear legitimate, we:

🐌 Slowed burst sending

🔁 Accepted retry attempts (like real mail servers)

This tricks Gmail into thinking we’re human, not a bot.

5️⃣ Live Monitoring Dashboard

We track key metrics every single day:

🚫 Spam complaints (Spamcop, AOL, etc.)

📉 IP/domain reputation

📬 Open, reply, and bounce rates

🌡️ Domain “temperature” by provider

⚠ Any suspicious spike? We pause, reroute, or restart warm-up.

6️⃣ Smart IP Rotation

If one IP gets too “hot,” we:

🔥 Rotate to a fresh IP

💡 Maintain steady reputation and deliverability

6️⃣ Smart IP Rotation

If one IP gets too “hot,” we:

🔥 Rotate to a fresh IP

💡 Maintain steady reputation and deliverability

7️⃣ Consistent Sending Windows

Forget 2 AM mass blasts.

We send emails at realistic business hours to build predictable sending patterns Gmail trusts.

8️⃣ Daily Inbox Placement Testing

We run tests across major email providers:

📧 Gmail

📨 Outlook

💼 Zoho

🛡️ Proton

This helps us avoid “silent” spam folder traps.

9️⃣ Human, Clean Copywriting

No AI-polished templates or “quick question” openers.

We write:

Natural tone

Light typos

Lowercase subject lines

This ensures Gmail doesn’t flag our emails as templated or robotic.

🔟 Cut Out Spam Triggers

We eliminate:

⛔ Link shorteners

⏳ Scheduling tools

📢 Pushy CTAs

Google flags these faster than you’d expect.

1️⃣1️⃣ Warmy.io = Our Secret Weapon

We use Warmy to:

🤖 Detect deliverability risks

🎯 Auto-warm 150K+ emails every month

🌍 Support multiple languages

🧑‍💼 Hands-off operation until inbox placement is stable

It’s our silent guardian operating in the background.