How Lettr evaluates and approves domains for email sending
When you add a new sending domain, Lettr evaluates it through an automated scoring system before allowing it to send emails. This step exists because email deliverability depends on shared infrastructure — every domain on the platform affects the reputation of the IP addresses used for sending. By screening domains before they can send, Lettr prevents bad actors from degrading delivery rates for legitimate senders and keeps the platform trusted by inbox providers like Gmail and Outlook.Most legitimate business domains pass this evaluation automatically within minutes. Understanding how the scoring works helps you set up your domain for the smoothest possible onboarding.
Every domain starts with a score of 100 points. The scoring system then runs a series of checks and deducts points for each risk signal it finds. At the end, the final score determines the outcome:
Score
Result
50–100
Approved automatically
Below 50
Blocked — flagged for manual review
A domain needs to retain at least half of its starting points to pass. This threshold is deliberately balanced — strict enough to catch clearly fraudulent domains, but lenient enough that most legitimate businesses pass without any manual intervention.
Certain domain name patterns are strongly correlated with spam campaigns. Domains matching any of these patterns receive a -50 point penalty, which alone drops the score to the borderline:
Very long random character strings (30+ alphanumeric characters before the TLD)
Excessive consecutive numbers (5+ digits in a row)
These patterns are checked against the full domain name before any other scoring runs. A domain like free-best-deals123456.xyz would trigger multiple patterns, but the penalty is applied once regardless of how many patterns match.
Beyond outright suspicious patterns, the domain name itself is evaluated for characteristics that correlate with lower legitimacy:
Characteristic
Penalty
Too short (fewer than 3 characters)
-20 points
Unusually long (more than 30 characters)
-10 points
Numeric-heavy (more than 50% digits)
-30 points
Uncommon or new TLD
-20 points
The TLD check compares against a list of trusted, well-established extensions. Trusted TLDs that incur no penalty include: .com, .net, .org, .edu, .gov, .io, .co, .app, .dev, .ai, .uk, .de, .fr, .nl, .be, .eu, .us, .ca, .au, .nz. Domains using newer or less common TLDs receive a -20 point deduction — not because they’re necessarily illegitimate, but because they carry less inherent trust signal.
Domain age is one of the strongest signals of legitimacy. Spammers frequently register new domains in bulk and abandon them once they’re blocklisted, so older domains have a much better track record. Lettr looks up the domain’s registration date via WHOIS and applies penalties accordingly:
Domain Age
Penalty
2+ years
No penalty
1–2 years
-10 points
6 months – 1 year
-20 points
1–6 months
No penalty
Less than 1 month
-40 points
WHOIS lookup unavailable
-20 points
Very new domains (less than 30 days old) receive the steepest age penalty (-40 points) because recently registered domains are disproportionately used for spam and phishing campaigns. If you’ve just registered your domain, waiting 30 days before adding it to Lettr significantly improves your chances of automatic approval.
The final and most nuanced check uses AI to analyze the website associated with your domain. When you register mail.example.com as a sending domain, the system visits example.com and evaluates it for legitimacy — looking at the main pages, following links to About, Contact, Privacy Policy, and Terms pages, and assessing the overall professionalism and authenticity of the site.The AI looks for positive signals that suggest a real business:
Clear company identity and branding
Physical business address and working contact information
Professional website design with original content
Privacy policy and terms of service
SSL certificate (HTTPS)
Social media presence with genuine activity
Industry credentials, certifications, or customer testimonials
It also watches for red flags that suggest spam, fraud, or low-quality operations:
No company information or anonymous ownership
Missing or fake contact details
Poor grammar and spelling across the site
Unrealistic promises, get-rich-quick schemes, or clickbait
Content copied from other websites
Phishing-like content mimicking known brands
Suspicious popup ads or aggressive marketing tactics
Based on this analysis, the AI assigns a score from 0 to 100, which maps to the following domain score penalties:
AI Score
Penalty
90–100
No penalty
80–89
-20 points
60–79
-40 points
40–59
-60 points
20–39
-80 points
0–19
-100 points
A domain with a clearly legitimate website and strong business presence may lose no points here at all, while a domain with no website or obviously fraudulent content can lose its entire starting score from this check alone.
After the scoring process completes, your domain transitions into one of three states:
Status
Meaning
Pending
Scoring is in progress — the system is running its checks
Approved
Domain passed the evaluation and can send emails
Blocked
Domain scored below 50 — flagged for manual review
Only domains with Approved status can send emails. If you try to send from a domain that’s still pending or has been blocked, the API will return an error indicating the domain is not configured or approved for sending.
If your domain scores below the approval threshold, there are several concrete steps you can take:
Check your website — Make sure your domain hosts a professional website with clear company information, contact details, and a privacy policy. The website analysis carries significant scoring weight, so even a simple but professional site can make the difference.
Wait for domain age — If your domain was registered within the last 30 days, waiting until it passes the one-month mark eliminates the steepest age penalty (-40 points). This alone may be enough to push your score above the threshold.
Contact support — Email support@lettr.com to request a manual review. Include details about your business, what you plan to send, and any context that explains why your domain may have triggered a low score. The Lettr team reviews blocked domains and can approve them manually when the business is clearly legitimate.
The three most common reasons for blocked domains are: very new domain registration (less than 30 days), no website content on the domain, and uncommon TLDs. Addressing these factors before adding your domain gives you the best chance of automatic approval.
If you’re planning to add a domain and want to maximize your chances of automatic approval, these steps will help:
Use a common TLD — .com, .net, .org, and country-code TLDs like .de or .co.uk carry the most trust
Register your domain early — Domains over 2 years old receive no age penalty at all, and even reaching the 6-month mark reduces the penalty significantly
Build your website first — A professional website with company information, contact details, and legal pages (privacy policy, terms of service) signals legitimacy to the AI analysis
Use HTTPS — An SSL certificate is a positive signal that the website is professionally maintained
Avoid spammy patterns — Keep your domain name conventional and professional, without excessive numbers, hyphens, or promotional prefixes
