Email Deliverability: How to Stop Landing in Spam

Crafting the perfect email means nothing if it lands in spam. Deliverability—whether your emails actually reach the inbox—is the foundation everything else depends on. Here’s how to make sure your emails get where they need to go.

Understanding Email Deliverability

When you send an email, it doesn’t go directly to recipients. It passes through multiple filters—your email service provider’s systems, the recipient’s email provider’s systems, and potentially corporate spam filters.

Each step evaluates whether your email looks legitimate, wanted, and safe. Your sender reputation, email content, and technical setup all influence this evaluation.

Authentication: The Non-Negotiable First Step

Email authentication proves you’re authorized to send from your domain. Three protocols matter: SPF tells receiving servers which mail servers can send email for your domain. DKIM adds a digital signature verifying the email hasn’t been altered in transit. DMARC tells servers what to do if SPF or DKIM checks fail and provides reporting.

Setting these up requires adding DNS records to your domain. Most email platforms including Brevo provide exact instructions for your specific setup. Do this before sending any significant volume.

Building Sender Reputation

Email providers track your sending patterns over time. High engagement improves reputation. Spam complaints damage it. Consistent sends are better than sporadic bursts.

If you’re starting fresh or moving to a new platform, warm up gradually. Don’t blast 50,000 emails on day one. Start with hundreds, increase to thousands over weeks, giving providers time to recognize you as legitimate.

List Quality Matters

Sending to people who don’t want your emails hurts deliverability. Every spam complaint tells email providers you’re sending unwanted messages.

Only email people who explicitly signed up. Double opt-in, where subscribers confirm via email after signing up, dramatically improves list quality. Never purchase email lists—they’re full of spam traps and uninterested people.

Clean your list regularly. Remove bounces immediately. Remove inactive subscribers quarterly. A smaller, engaged list outperforms a larger, unresponsive one.

Content That Avoids Spam Filters

Certain content triggers spam filters. Excessive use of spam-associated words—FREE, GUARANTEED, ACT NOW—can hurt. So can all-caps text, excessive exclamation points, and too many images with little text.

More sophisticated filters look at patterns. Does this email resemble spam that’s been reported before? Is the content consistent with what this sender typically sends?

The best approach: write genuine, valuable content for people who want it. Don’t try to game filters—write for humans.

Technical Hygiene

Use a custom domain, not a free email address like @gmail.com. Sending marketing email from free addresses hurts credibility and often triggers spam filters.

Include a physical mailing address in your emails—it’s legally required in many jurisdictions and signals legitimacy.

Ensure your unsubscribe link works and is easy to find. Making unsubscribing difficult just encourages spam complaints instead.

Monitoring and Improving

Watch your metrics. Bounce rates above 2% suggest list quality issues. Spam complaint rates above 0.1% indicate problems with content or consent. Sudden drops in open rates might mean deliverability issues.

Many platforms offer deliverability tools and reports. Brevo provides delivery analytics showing how your emails performed across different email providers. Use these insights to identify and fix issues.

Consider using inbox placement testing tools periodically. These services send test emails to various providers and report whether you hit the inbox, spam folder, or were blocked entirely.

When Things Go Wrong

If you suddenly see deliverability tank, investigate immediately. Check for authentication issues—did something change with your DNS settings? Review recent content for anything that might trigger filters. Look for unusual activity that might suggest your account was compromised.

Sometimes you end up on email blacklists. Services like MXToolbox let you check your domain and IP against known blacklists. Most blacklists have delisting procedures if you can demonstrate the problem is fixed.

The Long Game

Deliverability is built over time through consistent, legitimate sending practices. There are no shortcuts—buying lists, ignoring consent, and sending low-quality content all catch up with you eventually.

Do the fundamentals right: authenticate your domain, build your list honestly, send content people actually want, and maintain good list hygiene. Your emails will reach the inbox, and you’ll have a sustainable email marketing program.