Your emails are only as good as their deliverability. A perfectly written message means nothing if it lands in spam — or never arrives at all.

Most B2B teams focus on copy and targeting while ignoring the infrastructure that determines whether their emails even get seen. The result: low open rates, wasted pipeline, and a sender reputation that quietly deteriorates.

This email deliverability checklist covers 10 specific checks you can run through before launching any outbound campaign. Each one is actionable, ordered by impact, and takes minutes — not days. For the full deep dive on each step, check out our complete email deliverability checklist guide.

1. Verify Every Email Address Before Sending

Hard bounces are the fastest way to wreck your sender reputation. Gmail, Yahoo, and Microsoft track your bounce rate at the domain level. Cross the 2% threshold and your domain reputation can take a serious hit — affecting deliverability across all your campaigns.

Run every email address through a verification tool that checks syntax, MX records, and mailbox existence before it enters any outbound sequence. Pay special attention to catch-all domains, which accept all emails at the server level and can't be verified by basic tools. Platforms like FullEnrich use triple verification across multiple providers to validate up to 80% of catch-all emails — reducing your bounce risk significantly.

Never skip this step. A single campaign to unverified addresses can damage your sender reputation for months. For a deeper look at verification tooling, read our email verification API guide.

2. Set Up SPF, DKIM, and DMARC

Email authentication tells inbox providers you are who you claim to be. Without these three protocols, your emails look identical to phishing attempts — and get treated accordingly.

SPF lists which IP addresses are allowed to send email on behalf of your domain. DKIM adds a cryptographic signature so receivers can confirm your message wasn't tampered with in transit. DMARC ties the two together and tells inbox providers what to do when authentication fails.

As of early 2026, major inbox providers have significantly tightened requirements for bulk senders. Google and Yahoo require DMARC authentication, and Microsoft has followed suit with similar policies. Start with p=none to monitor, then tighten to p=quarantine or p=reject once all legitimate senders are authenticated. Keep your SPF record under the 10 DNS lookup limit — exceed it and the check fails silently.

3. Send From a Dedicated Domain

Never send cold emails from your primary business domain. If a cold campaign damages your sender reputation, it takes everything else down with it — your CEO's investor emails, your support team's replies, your marketing newsletters.

Set up a separate domain that's clearly related to your brand (e.g., outreach.yourcompany.com or mail.yourcompany.com). Apply the same SPF, DKIM, and DMARC setup. This way, if something goes wrong with outbound, your main domain stays clean.

For a more detailed breakdown of domain strategy, see our guide on primary domain vs cold email domain.

4. Warm Up New Domains Before Sending at Scale

A brand-new domain has zero reputation. Inbox providers treat unknown senders as guilty until proven innocent. If you immediately blast hundreds of cold emails from a fresh domain, nearly all of them will land in spam.

Email warmup builds your domain's reputation gradually by sending emails that generate positive engagement signals — opens, replies, and inbox moves. Start with 10–20 emails per day and increase volume slowly over 2–4 weeks. Target engaged contacts first to show ISPs that real people want your emails.

Dedicated email warmup tools automate this process by simulating real engagement patterns across a network of inboxes. Don't skip warmup — even with perfect authentication, a cold domain will land in spam.

5. Keep Bounce Rates Under 2%

Your bounce rate is a direct signal to inbox providers about the quality of your data. Hard bounces (invalid addresses) are the worst — they tell Gmail and Microsoft that you're sending to people who don't exist, which is a classic spam pattern.

Set up your email platform to automatically suppress hard bounces after the first occurrence. Track soft bounces (temporary issues like full mailboxes) and remove addresses that soft-bounce three or more times in a row.

The target: keep total bounce rate below 2% and hard bounce rate below 0.5%. If you're consistently above that, your email verification process has a gap.

6. Clean Your List at Least Monthly

Email lists decay. People change jobs, companies shut down domains, and addresses that were valid last quarter become hard bounces today. In B2B, contact data can decay significantly each year — meaning a list left untouched for 12 months may have a sizable portion of dead addresses.

Run your active sending list through an email verifier every 30 days. Remove addresses that have gone invalid. Suppress anyone who hasn't opened or clicked in 90+ days for marketing emails. For cold outbound, verify at the point of enrichment and again before loading into your outbound sequence.

This is closely tied to your broader email deliverability best practices — list hygiene is one of the highest-impact levers you have.

7. Add a One-Click Unsubscribe Link

Spam complaints are more damaging than bounces. When a recipient marks your email as spam, that signal goes directly to the inbox provider. Too many complaints and your domain gets deprioritized across every recipient — not just the one who complained.

Google and Yahoo now require a one-click unsubscribe header for bulk senders. But even for cold outbound, include a clear, easy-to-find unsubscribe link. The math is simple: a recipient who unsubscribes quietly is far better for your reputation than one who hits the spam button because they couldn't find another way out.

Keep complaint rates as low as possible — many ESPs recommend staying below 0.1%. If you're consistently above that, your targeting or messaging needs work.

8. Monitor Your Sender Reputation Weekly

Your sender reputation is a score that inbox providers assign based on your sending history. A good reputation means your emails reach the inbox. A bad one means they get filtered — regardless of how good your content is.

Check your reputation at least once a week using free tools like Google Postmaster Tools (for Gmail), Microsoft SNDS (for Outlook), and Sender Score for a general rating. Watch for sudden dips — they usually indicate a problem with list quality, a spike in complaints, or an authentication failure.

For the full stack of monitoring tools, see our guide to email deliverability tools.

9. Write Like a Human, Not a Marketing Bot

Modern spam filters use machine learning to analyze content patterns. They don't just flag individual words — they evaluate the overall pattern of your message. Emails that look like mass marketing get filtered. Emails that look like one person writing to another get through.

Keep emails short and text-based. Minimize images, avoid HTML-heavy templates for cold outreach, and skip URL shorteners (spam filters flag them). Write in a conversational tone. Use the recipient's name, reference something specific to them, and ask a genuine question.

Avoid classic spam triggers: ALL CAPS, excessive exclamation marks, words like "free," "guaranteed," and "act now." But the bigger principle is simpler — if your email reads like a template, it'll be treated like one.

10. Test Inbox Placement Before Every Major Campaign

Your email platform says "delivered" — but that doesn't mean your message landed in the inbox. It means the receiving server accepted it. It could still be sitting in spam, promotions, or a junk folder where no one will see it.

Inbox placement testing sends your actual email to seed addresses across Gmail, Outlook, Yahoo, and other providers, then reports where each one landed. Run this test before every major campaign or sequence launch — especially after any change to your domain, content template, or sending tool.

Tools like GlockApps, MailReach, and Mail-tester.com offer quick placement tests. Treat inbox placement as the final quality gate — if you're landing in spam for any major provider, fix the issue before you scale.

Build Deliverability Into Your Process

Email deliverability isn't a one-time setup. It's an ongoing system — verify your data, authenticate your domain, warm up before scaling, keep your lists clean, and monitor your reputation.

The teams that consistently achieve strong inbox placement aren't doing anything exotic. They're running through checks like these before every campaign. Build these 10 steps into your standard operating procedure and your emails will reach the people they're meant for.

Have questions about specific checks? Read our email deliverability checklist FAQ for detailed answers to the most common questions.