Brevo Spam Prevention: Keep Emails Out of Spam Folder

Landing in the spam folder is a silent killer for email marketing. Your open rates drop, your click rates collapse, and subscribers who actually want your email stop receiving it — all without any error message or warning. Understanding how spam filters work and applying a systematic approach in Brevo will keep your emails consistently in the inbox.

How Modern Spam Filters Work

Spam filters in 2026 are far more sophisticated than simple keyword detectors. Modern filters used by Gmail, Outlook, and Yahoo evaluate hundreds of signals simultaneously:

Sender reputation signals:

• IP address reputation
• Domain age and history
• Spam complaint rate
• Bounce rate
• Engagement history (open rates, click rates, replies)

Authentication signals:

• SPF pass/fail
• DKIM valid/invalid
• DMARC alignment

Content signals:

• Spam trigger words and phrases
• HTML code quality
• Image-to-text ratio
• Link reputation and redirect chains
• Missing or deceptive content (misleading subject line vs email body)

Engagement signals:

• Recipient behaviour patterns (do they open emails from you?)
• Whether past emails were moved to spam by recipients
• Whether recipients reply to your emails

No single signal determines spam classification. Filters weigh all these factors together. A slightly spammy subject line from a highly trusted sender will sail into the inbox. A clean subject line from a new sender with no authentication will get filtered.

Brevo's Built-In Spam Check

Before sending any campaign, use Brevo's spam check feature. In the campaign review step, click Check for Spam. Brevo analyses your email and provides:

• SpamAssassin score — The industry-standard spam scoring tool. A score under 5.0 is generally safe; above 5.0 starts triggering filters for many providers.
• Specific flags — Brevo identifies which elements contributed to your score and what to fix.

Run the spam check for every campaign, even if your previous campaigns passed. Content changes can introduce new flags.

Avoiding Spam Trigger Words

Certain words and phrases have been so heavily associated with spam over the years that their presence in a subject line or email body automatically increases your spam score. Common trigger phrases to avoid:

In subject lines:

• "Free!!!" / "FREE" (all caps)
• "Guaranteed" / "100% guaranteed"
• "Act now" / "Act immediately"
• "Limited time offer" (used excessively)
• "You have been selected"
• "Winner" / "You've won"
• "No credit card required" (ironic but flagged)
• "Make money fast"
• "Work from home"
• "Earn cash"

In email body:

• "Click here" (as link anchor text — use descriptive text instead)
• "Buy now" (in isolation — "Get your copy" or "Start your trial" is better)
• "This is not spam" (a red flag that screams spam)
• Dollar signs repeated: $$$, $$$$
• "Dear friend" (classic spam opener)

Formatting spam signals:

• Excessive exclamation marks (!!!)
• All-caps sentences or subject lines
• Red, bright green, or yellow text (used for emphasis by spammers)
• More than 1-2 emoji in subject lines

Content Best Practices

Maintain a healthy image-to-text ratio. Emails that are mostly images contain very little text for spam filters to analyse, which makes them suspicious. Aim for at least 60% text by visible area. Never send an email that is a single large image with no text.

Write natural, flowing copy. Spam often contains keyword-stuffed, grammatically poor copy. Write like a human communicating with another human. Good copy is also better spam-filter-bypassing copy.

Use consistent formatting. Wildly varying font sizes, multiple font families in the same email, and inconsistent spacing are hallmarks of hastily assembled spam. Keep your typography consistent.

Include your physical address. CAN-SPAM (US), CASL (Canada), and GDPR (EU) all require a physical mailing address in commercial emails. Missing this is both a legal risk and a spam signal. Add your business address to Brevo's email footer template.

Have a clear unsubscribe link. Brevo adds this automatically, but make sure it is visible and easy to find. Hiding the unsubscribe link leads to spam complaints, which are far more damaging than unsubscribes.

Link Hygiene

Every link in your email contributes to your spam score. Problematic links that filters scrutinise:

URL shorteners — Links through bit.ly, tinyurl, or similar services obscure the destination and are commonly associated with spam. Use full URLs or your own branded short domain.

Redirect chains — A link that goes through three or four redirects before reaching the destination is suspicious. Wherever possible, link directly to the destination page.

Mismatched anchor text — A link that says "Visit our blog" but points to a checkout page is a deceptive practice flagged by spam filters. The anchor text should accurately describe the destination.

Links to low-reputation domains — If you link to a website that appears on spam blocklists, your email inherits some of that reputation. Audit your external links.

Too many links — An email with 20+ links looks like a link farm. Use the minimum number of links needed to serve your campaign goal.

Testing Tools

Beyond Brevo's built-in spam check, use these external tools:

Mail Tester (mail-tester.com) — Send a test email to a specific address and receive a detailed spam score report covering authentication, content, and blacklist status.

GlockApps — A paid tool that shows exactly where your email lands (inbox, spam, or promotions tab) across Gmail, Outlook, Yahoo, and other major email clients.

MXToolbox — Check if your sending IP or domain is on any major blacklist.

Litmus or Email on Acid — Email rendering tools that also offer spam testing across multiple email clients.

Brevo's Spam Check Feature Walkthrough

1. Complete your email design in the Brevo campaign editor
2. In the campaign review step, click "Spam Check" or "Test"
3. Review the SpamAssassin score
4. Address each flagged issue:
   • Score contributions from the subject line → rewrite the subject
   • Score contributions from content → remove trigger phrases
   • Score contributions from HTML errors → use the Brevo editor rather than pasting custom HTML
   • Score contributions from missing unsubscribe → verify Brevo footer is intact
5. Re-run the check after making changes
6. Aim for a score below 3.0 for maximum inbox placement

Brevo Plan Comparison

Plan	Price	Emails/Month	Key Features
Free	$0/forever	300/day	Unlimited contacts, email campaigns, basic CRM, Brevo branding
Starter	From $9/month	5,000	No daily cap, no Brevo logo, basic reporting, email & phone support
Business	From $18/month	20,000	Marketing automation, A/B testing, advanced stats, multi-user access
Enterprise	Custom pricing	Unlimited	Dedicated IP, SSO/SAML, custom onboarding, dedicated account manager

Run Brevo's spam check before every single campaign send — it takes 30 seconds and can save you from silently delivering to spam folders for your entire list.