Content Deliverability Checker

The Content Deliverability Checker analyzes your email in real-time as you write, helping you avoid spam filters before you hit send. Look for the score button in the editor toolbar - it shows your current deliverability score from 0-100.

How It Works

The checker runs automatically as you write (with a 3-second delay after you stop typing to save CPU). It analyzes 9 key factors that affect whether your email lands in the inbox or spam folder.

The 9 Deliverability Checks

1. Unsubscribe Link (25 points)

Required by law (CAN-SPAM, GDPR) and expected by all email providers.

• Use the {{unsubscribeUrl}} variable in your email
• Type / in the editor and select "Unsubscribe Link" to insert it
• Place it in your footer for best practice

2. Physical Address (15 points)

Required by CAN-SPAM - you must include a valid physical mailing address.

Three ways to pass this check:

1. Use the @org-adresse variable (recommended)
2. Include your organization's address text directly
3. Include any address matching standard formats (US, EU, PO Box)

Detected address formats:

• US: 123 Main St, City, CA 90210
• EU/French: 123 rue de la Paix, 75001 Paris
• PO Box: P.O. Box 123 or Boîte Postale 123

3. Subject Line Length (15 points)

Optimal subject lines are 20-70 characters.

Length	Score	Issue
20-70 chars	15/15	Optimal
1-19 chars	7/15	Too short - may look spammy
71+ chars	7/15	Too long - gets truncated on mobile
Empty	0/15	Missing subject line

Tips:

• First 30 characters are most important (mobile preview)
• Put key information at the beginning
• Avoid ALL CAPS in subject lines

4. Image-to-Text Ratio (10 points)

Emails with too many images and not enough text trigger spam filters.

Rule: Maximum 1 image per 200 words of text.

• All-image emails are blocked by many spam filters
• Include alt text for all images
• Balance visual content with meaningful text

5. Spam Trigger Words (10 points)

Certain words and phrases are associated with spam. The checker detects 270+ spam trigger words in 4 languages (English, French, Spanish, Italian).

High-risk categories:

Category	Examples
Urgency	"act now", "limited time", "expires today", "urgent"
Financial	"free money", "earn cash", "double your money", "get rich"
Phishing	"click here", "verify your account", "confirm your identity"
Scams	"congratulations", "you're a winner", "you have been selected"
Health	"weight loss", "no prescription", "miracle cure"

Penalty: -3 points per spam word found (minimum 0 points).

Pro tip: Use the "Unspam" AI command to automatically rewrite spam trigger words with deliverability-safe alternatives.

6. Link Count (5 points)

Too many links can trigger spam filters.

Links	Score	Recommendation
0-5	5/5	Good
6+	2/5	Consider reducing

Tips:

• Focus on 1-3 primary call-to-action links
• Combine multiple links into a single "Learn more" page if needed

7. No Shortened URLs (10 points)

URL shorteners (bit.ly, tinyurl, etc.) are heavily penalized by spam filters because they're commonly used to hide malicious links.

Blocked shorteners:

• bit.ly, tinyurl.com, t.co, goo.gl
• ow.ly, is.gd, buff.ly, adf.ly
• tiny.cc, cutt.ly, rb.gy, and more

Solution: Use your own domain for tracking links. Lumail automatically tracks clicks without using shorteners.

8. No ALL CAPS Abuse (5 points)

Excessive use of ALL CAPS words triggers spam filters and looks unprofessional.

Rule: Maximum 2 words with 4+ uppercase letters.

Allowed (not counted):

• Common acronyms: API, URL, HTML, CEO, ROI, AWS, etc.
• Brand names: CLAUDE, NOW (when part of product names)
• Standard abbreviations: LLC, INC, USA, FAQ

Flagged:

• Marketing words in caps: FREE, SALE, URGENT, AMAZING
• Multiple caps words: "GET YOUR FREE BONUS NOW"

9. Text Length (5 points)

Very short emails may be flagged as spam.

Word Count	Score	Status
50+ words	5/5	Good
20-49 words	2/5	Short
< 20 words	0/5	Too short

Using the Unspam AI Command

The Unspam feature automatically rewrites spam trigger words with deliverability-safe alternatives while keeping your message's meaning.

To use it:

1. Click the AI button (robot icon) in the editor toolbar
2. Select "Unspam" → "Improve deliverability"
3. Wait for the AI to process your email

Example transformations:

Spam Word	Safe Alternative
"Act now!"	"Get started today"
"Click here"	"Learn more"
"Free money"	"Bonus" or "Benefit"
"Congratulations!"	"Great news!"
"You have been selected"	"You're invited"
"100% guaranteed"	"We stand behind this"
"Limited time offer"	"Currently available"

The AI preserves:

• Your email's original language (French stays French, etc.)
• All formatting (bold, links, images)
• All variables ({{unsubscribeUrl}}, @name, etc.)
• The tone and intent of your message

Score Interpretation

Score	Color	Status	Action
90-100	Green	Excellent	Ready to send
70-89	Yellow	Good	Review warnings
50-69	Orange	Needs work	Fix issues before sending
0-49	Red	Poor	Major issues to address

Best Practices Summary

Do

• Always include an unsubscribe link
• Add your physical address (use @org-adresse)
• Keep subject lines 20-70 characters
• Write at least 50 words of content
• Use your own domain for links
• Run "Unspam" before sending important campaigns

Don't

• Use URL shorteners (bit.ly, tinyurl)
• Write in ALL CAPS
• Use spam trigger words ("free", "urgent", "click here")
• Send image-only emails
• Include too many links (keep it under 6)

Related Documentation

• Email Deliverability Score - Post-send deliverability metrics (bounces, complaints)
• Engagement Score - Open and click rate analysis
• Variables - Using {{unsubscribeUrl}} and @org-adresse
• Send Email API - Apply deliverability best practices to API emails
• Email Domains - Configure SPF, DKIM, DMARC for better deliverability