Email deliverability is about making sure your emails reach the inbox, not the spam folder. This guide covers the three pillars of deliverability: authentication, reputation, and content.

Pillar 1: Authentication (SPF, DKIM, DMARC)

Authentication proves to receiving servers that you’re authorized to send email for your domain.

SPF (Sender Policy Framework)

SPF lists which mail servers can send email on your domain’s behalf.

// Add this TXT record to your domain's DNS:
v=spf1 include:spf.cyberpersons.com ~all

• include:spf.cyberpersons.com authorizes all CyberPanel mail servers
• ~all tells receivers to soft-fail emails from unauthorized servers
• SPF fail adds +5 to CyberMail’s spam score; soft-fail adds +2

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to every email, proving it wasn’t tampered with in transit.

• CyberMail automatically signs all outgoing emails with your domain’s DKIM key
• The public key is published as a TXT record at postal._domainkey.yourdomain.com (sending) or mail._domainkey.yourdomain.com (hosting)
• Keys are 2048-bit RSA, generated automatically when you add a domain

DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM fail.

// Recommended DMARC record:
v=DMARC1; p=quarantine; rua=mailto:[email protected]

• p=quarantine — Failed emails are sent to spam (start here)
• p=reject — Failed emails are rejected entirely (move to this after confirming everything works)
• rua=mailto: — Receive aggregate reports about authentication results

See Domain Verification & DNS Setup for step-by-step DNS configuration.

Pillar 2: Reputation

Your domain and account reputation directly affect inbox placement.

Domain Reputation Scoring

CyberPanel tracks your domain reputation on a 0–100 scale:

How to Maintain Good Reputation

• Clean your lists: Remove invalid addresses and unengaged subscribers regularly
• Use double opt-in: Require email confirmation for new subscribers
• Honor unsubscribes: Process unsubscribe requests immediately
• Monitor bounces: Remove hard-bounced addresses from your list
• Warm up gradually: When starting, send to small batches and increase volume over days

Pillar 3: Content

Even with perfect authentication and reputation, poor content can trigger spam filters.

Best Practices

• Avoid spam trigger words in subject lines (“FREE!!!”, “Act now!!!”, all-caps)
• Maintain a good text-to-image ratio (don’t send image-only emails)
• Include a plain-text version alongside HTML
• Use a consistent From name and address
• Include a physical mailing address (required by CAN-SPAM)
• Always include an unsubscribe link in marketing emails

CyberMail Anti-Spam Protection

CyberMail includes built-in anti-spam that scans both incoming and outgoing email:

• DNSBL checking: Queries Spamhaus DBL, SURBL, and Barracuda blocklists
• URL scanning: Checks links against blocklists, detects suspicious TLDs and IP-based URLs
• SPF verification: Validates sender authorization
• Content scoring: Assigns a spam score; emails above the threshold are flagged or rejected

Multi-Node Failover

CyberPanel Email runs on 4 geographically distributed nodes. If one node is down or busy, your email automatically routes through another node — ensuring 99.9% uptime.

Deliverability Checklist

Related Guides

• Documentation Hub
• Getting Started with Email Delivery
• Domain Verification & DNS Setup
• Email Analytics and Logs
• Plans, Pricing, and Rate Limits

← Back to Documentation Hub