The 7-Step Email Deliverability Checklist Every Marketer Needs to Boost Open Rates

If your email campaigns are landing in the spam folder, you’re losing sales, trust, and time. I’ve seen a 30% drop in revenue simply because a client’s welcome series never reached the inbox. That’s why a solid deliverability checklist is not a nice‑to‑have – it’s a must‑have.

Step 1 – Verify Your Sending Domain

Before you hit send, make sure the domain you’re sending from is verified. This means setting up SPF, DKIM, and DMARC records.

• SPF (Sender Policy Framework) tells receiving servers which IP addresses are allowed to send mail for your domain.
• DKIM (DomainKeys Identified Mail) adds a digital signature to each message so the receiver can prove it really came from you.
• DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together and tells the inbox what to do if a message fails the checks.

I once forgot to add DKIM for a new sub‑domain. The result? All my test emails bounced back with a “failed authentication” note. A quick DNS update fixed it, and the open rate jumped from 12% to 28% overnight.

Step 2 – Clean Your List Regularly

A list full of stale or invalid addresses is a deliverability nightmare. Run a weekly scrub to remove:

• Hard bounces (permanent failures)
• Soft bounces that persist for more than three campaigns
• Unengaged subscribers who haven’t opened anything in the last six months

There are cheap tools that can do this automatically. The cost of a clean list is far lower than the cost of a damaged sender reputation.

Step 3 – Warm Up New IPs

If you’re moving to a new IP address, start slow. Send a small volume to your most engaged contacts first, then gradually increase the volume over 2‑4 weeks. This signals to ISPs that you’re a legitimate sender, not a spammer.

When I first switched to a dedicated IP for a high‑volume client, we sent 5,000 emails a day to our top 10% of openers. By week three we were up to 50,000 daily without any deliverability warnings.

Step 4 – Keep Your Sending Frequency Consistent

Inconsistent sending looks suspicious to inbox providers. Choose a cadence that you can stick to—whether it’s daily, weekly, or monthly—and keep it. If you need to pause, let your audience know in advance.

I once ran a “flash sale” email blast after a month of silence. The open rate plummeted because the inboxes didn’t recognize the sender. The next week we sent a re‑engagement series, and the rates recovered.

Step 5 – Craft a Clean, Spam‑Free Subject Line

Subject lines are the first thing spam filters look at. Avoid:

• All caps
• Excessive punctuation (!!!)
• Spam trigger words like “free”, “guarantee”, “winner”

Instead, be clear and specific. “Your weekly roundup is here” works better than “FREE! Open now!!!”.

A quick A/B test I ran showed a 15% lift in opens when we removed the word “free” from the subject line and added the recipient’s first name.

Step 6 – Optimize Your Content for Deliverability

Even if your subject line passes, the body can still get flagged. Follow these rules:

• Keep the text‑to‑image ratio balanced (about 60% text, 40% images).
• Use a single, clear “From” name and email address.
• Include a plain‑text version of the email.
• Avoid large attachments; link to files instead.

One client loved using high‑resolution graphics, but the emails kept landing in the Promotions tab. We reduced the image size and added a concise text version, and the inbox placement improved dramatically.

Step 7 – Monitor, Analyze, and React

Deliverability is not a set‑and‑forget task. Keep an eye on:

• Bounce rates (aim for <2%)
• Spam complaint rates (stay under 0.1%)
• Sender reputation scores (most ESPs provide a dashboard)
• Engagement metrics (opens, clicks, conversions)

Set up alerts for any spikes in bounces or complaints. When I noticed a sudden rise in soft bounces, I discovered a new firewall rule at the recipient’s corporate network. A quick call to their IT team cleared the block and restored normal delivery.

Putting It All Together

The checklist may look long, but each step builds on the last. Think of it as a daily health routine for your email program: verify, clean, warm up, stay consistent, write smart, keep the content tidy, and watch the numbers. When you treat deliverability like a habit, the open rates follow naturally.

At Inbox Insights we run this checklist before every major campaign. It’s saved us from countless “email not delivered” headaches and helped us keep our clients’ inboxes happy.