# EmailCloud.com — LLM Discovery & API Documentation

> Everything Email — Free Security Tools, Honest Reviews, Expert Guides, 24 Diagnostic APIs

---

## Site Overview

EmailCloud.com is an independent email authority hub with 30+ years in the email ecosystem. We provide:
- **24 free diagnostic tools** (SPF checker, DMARC checker, subject line grader, spam word detector, warmup calculator, ROI analyzer, and more)
- **40+ honest platform reviews** (email marketing, automation, CRM, transactional, security)
- **39 head-to-head comparisons** (Mailchimp vs GetResponse, Klaviyo vs Omnisend, etc.)
- **130+ timeline articles** (email history 1971-2026, ISP era, AOL, webmail, MTA wars, DMARC adoption, Gmail authentication mandates, newsletter boom, etc.)
- **Enterprise email security layer** (SPF/DMARC/DKIM validation, blacklist checking, header analysis, compliance guides)
- **Interactive planning tools** (warmup schedules, send time optimization, email frequency calculators, ROI projections)

**Website:** https://emailcloud.com
**Pages:** 306 static pages (zero JavaScript on content, all tools run client-side)

---

## API Access

### Base URL
```
https://api.emailcloud.com
```

### MCP Discovery
```
https://api.emailcloud.com/.well-known/mcp.json
```

### Health Check
```
GET /api/health
```

### API Statistics
```
GET /api/stats
```

### Get Free API Key (Optional)
```
POST /api/register
```

All tools are free to try — no signup for your first check. After that, register with your email at POST /api/register for continued access. API keys enable usage tracking and higher rate limits.

### CORS Policy
- **Origins allowed:** emailcloud.com, www.emailcloud.com, localhost:4321, *.anthropic.com
- **Methods:** GET, POST, OPTIONS
- **Headers:** Content-Type, Authorization

### Rate Limits
- `/api/generate` (deliverability test): 10 requests per minute per IP
- All other endpoints: Unlimited (instant tools, no queue)

### Authentication
Optional. Include API key as `Authorization: Bearer YOUR_API_KEY` header for tracked access.

---

## 24 Diagnostic Tools (Grouped by Function)

### 1. Deliverability Testing (2 tools)

#### Generate Test Inbox
Create a temporary email address to send a test message for full inbox placement analysis.
- **Endpoint:** `GET /api/generate`
- **Parameters:**
  - `domain` (optional): Your sending domain (default: emailcloud.com)
- **Response:** `{ email_id, test_email_address, expires_at }`
- **Lifetime:** 2 hours
- **Frontend:** https://emailcloud.com/tools/deliverability-check
- **Use case:** Send a test message to the generated inbox, then poll for deliverability report

#### Get Deliverability Report
Retrieve 12-point analysis: inbox placement, spam folder detection, authentication status, content filtering, ISP feedback.
- **Endpoint:** `GET /api/results/{email_id}`
- **Parameters:**
  - `email_id` (required, path): ID from /api/generate
- **Response:** `{ status, inbox_placement, authentication, content_analysis, isp_feedback, spam_score, 12_point_analysis }`
- **Frontend:** https://emailcloud.com/tools/deliverability-check
- **Polling interval:** Check every 5-10 seconds; analysis takes 2-5 minutes

---

### 2. DNS & Domain Authentication Checks (5 tools)

#### SPF Checker
Validate SPF record syntax, count DNS lookups, check for errors and warnings.
- **Endpoint:** `GET /api/tools/spf/{domain}`
- **Parameters:**
  - `domain` (required, path): Domain to check (e.g., example.com)
- **Response:** `{ valid, lookups, includes, qualifiers, warnings, errors, explanation }`
- **Frontend:** https://emailcloud.com/tools/spf-checker
- **Use case:** Validate SPF record on your sending domain; check lookup count (max 10 limit)

#### DMARC Checker
Analyze DMARC policy, reporting configuration, alignment mode, and suggested improvements.
- **Endpoint:** `GET /api/tools/dmarc/{domain}`
- **Parameters:**
  - `domain` (required, path): Domain to check
- **Response:** `{ found, policy, reporting_addresses, alignment_mode, subdomain_policy, percentage, suggestions }`
- **Frontend:** https://emailcloud.com/tools/dmarc-checker
- **Use case:** Verify DMARC enforcement level; recommend policy progression (none → quarantine → reject)

#### MX Lookup
Find mail servers, detect ESP (mailgun, sendgrid, etc.), check MTA reputation.
- **Endpoint:** `GET /api/tools/mx/{domain}`
- **Parameters:**
  - `domain` (required, path): Domain to check
- **Response:** `{ mx_records, priority, host, ip_address, esp_detected, reputation }`
- **Frontend:** https://emailcloud.com/tools/mx-lookup
- **Use case:** Identify mail handling infrastructure; discover ESP provider from MX records

#### Blacklist Checker
Check domain or IP against 14 major DNS blocklists (Spamhaus, SpamCop, Barracuda, etc.).
- **Endpoint:** `GET /api/tools/blacklist/{target}`
- **Parameters:**
  - `target` (required, path): Domain or IP address to check
- **Response:** `{ listed, blocklists: [ { name, listed, removal_url } ], reputation_score }`
- **Frontend:** https://emailcloud.com/tools/blacklist-checker
- **Use case:** Monitor domain/IP reputation; detect unexpected blocklist additions

#### Deliverability Score
Combined A-F grade based on SPF, DKIM, DMARC, BIMI, reverse DNS, and authentication stack.
- **Endpoint:** `GET /api/tools/deliverability-score/{domain}`
- **Parameters:**
  - `domain` (required, path): Domain to grade
- **Response:** `{ grade (A-F), spf_score, dkim_score, dmarc_score, bimi_score, reverse_dns_score, overall_score }`
- **Frontend:** https://emailcloud.com/tools/deliverability-score
- **Use case:** Quick 10-second authentication health check; guide domain hardening priorities

---

### 3. Record Builders (2 tools)

#### SPF Record Builder
Generate valid SPF record from selected services (Mailchimp, SendGrid, Mailgun, Klaviyo, etc.).
- **Endpoint:** `POST /api/tools/spf-builder`
- **Parameters:**
  - `domain` (required): Your domain
  - `includes` (required, array): [ "mailchimp", "sendgrid", "mailgun", "klaviyo", "twilio", ... ]
  - `ips` (optional, array): Additional IPs to authorize
- **Response:** `{ spf_record (string), lookup_count, warnings }`
- **Frontend:** https://emailcloud.com/tools/spf-record-builder
- **Use case:** Generate SPF record from your ESP stack; avoid manual mistakes

#### DMARC Record Generator
Build DMARC TXT record with policy settings, reporting addresses, subdomain policy.
- **Endpoint:** `POST /api/tools/dmarc-generator`
- **Parameters:**
  - `domain` (required): Your domain
  - `policy` (required): "none" | "quarantine" | "reject"
  - `alignment` (required): "strict" | "relaxed"
  - `subdomain_policy` (optional): "none" | "quarantine" | "reject"
  - `percentage` (optional, default 100): 0-100, percentage of emails to apply policy to
  - `rua_email` (optional): Aggregate report email
  - `ruf_email` (optional): Forensics report email
  - `bimi_bitmap` (optional): BIMI record location
- **Response:** `{ dmarc_record (string), policy_explanation, next_steps }`
- **Frontend:** https://emailcloud.com/tools/dmarc-generator
- **Use case:** Generate DMARC policy TXT record; optionally set up BIMI for brand logo in inbox

---

### 4. Email Content Analysis (5 tools)

#### Subject Line Grader
Score subject lines on 12 factors: length, power words, questions, punctuation, emojis, personalization, urgency, specificity, CTA clarity, mobile rendering, spam triggers, deliverability risk.
- **Endpoint:** `POST /api/tools/subject-grade`
- **Parameters:**
  - `subject_line` (required): The subject line to grade (max 200 chars)
  - `audience` (optional): "b2b" | "b2c" | "newsletter" | "promotion" | "transactional"
  - `industry` (optional): "ecommerce" | "saas" | "nonprofit" | "finance" | "health" | etc.
- **Response:** `{ grade (A+ to F), score (0-100), factors: [ { name, score, feedback } ], suggestions }`
- **Frontend:** https://emailcloud.com/tools/subject-line-grader
- **Use case:** Optimize subject lines before send; benchmark against industry standards

#### A/B Subject Line Tester
Compare two subject lines side-by-side with detailed scoring on each factor.
- **Endpoint:** `POST /api/tools/ab-test`
- **Parameters:**
  - `subject_a` (required): First subject line
  - `subject_b` (required): Second subject line
  - `audience` (optional): "b2b" | "b2c" | "newsletter" | etc.
- **Response:** `{ subject_a: { grade, score, factors }, subject_b: { grade, score, factors }, winner, analysis }`
- **Frontend:** https://emailcloud.com/tools/ab-subject-line-tester
- **Use case:** Test subject lines before A/B testing in production; predict winner

#### Spam Word Checker
Detect spam trigger words and phrases by severity (red flag, yellow flag, low risk).
- **Endpoint:** `POST /api/tools/spam-words`
- **Parameters:**
  - `text` (required): Email body or subject line (max 5000 chars)
  - `include_emoji` (optional, default true): Flag emoji abuse
  - `include_caps` (optional, default true): Flag ALL CAPS sections
- **Response:** `{ spam_score (0-100), triggers: [ { word, severity, count } ], recommendations }`
- **Frontend:** https://emailcloud.com/tools/spam-word-checker
- **Use case:** Clean marketing copy before send; reduce spam folder placement

#### Email Character Counter
Count characters, estimate pixel width, preview how email renders in mobile clients.
- **Endpoint:** `POST /api/tools/character-count`
- **Parameters:**
  - `email_body` (required): Email HTML or plain text
  - `include_preheader` (optional): Preheader text
  - `preview_clients` (optional, array): [ "gmail", "outlook", "apple", "mobile_safari" ]
- **Response:** `{ character_count, word_count, pixel_width, preview_images: [ { client, image_url } ], warnings }`
- **Frontend:** https://emailcloud.com/tools/email-character-counter
- **Use case:** Check email length before send; preview across clients

#### CTA Contrast Checker
Check WCAG AA/AAA contrast ratios for email buttons and links (required for accessibility, improves CTR).
- **Endpoint:** `POST /api/tools/contrast`
- **Parameters:**
  - `foreground_color` (required): Hex color (e.g., #FFFFFF)
  - `background_color` (required): Hex color (e.g., #0066CC)
  - `font_size` (optional, default 16): Pixel size
- **Response:** `{ contrast_ratio, wcag_aa (pass/fail), wcag_aaa (pass/fail), recommendations }`
- **Frontend:** https://emailcloud.com/tools/email-contraster
- **Use case:** Ensure buttons are accessible and visible; improve CTR

---

### 5. Headers & Email Structure (2 tools)

#### Email Header Analyzer
Parse raw email headers, trace delivery path, check authentication (SPF/DKIM/DMARC/BIMI), identify original sender.
- **Endpoint:** `POST /api/tools/headers`
- **Parameters:**
  - `headers` (required): Raw email headers (full text from "view source")
  - `body` (optional): Email body for content analysis
- **Response:** `{ from, to, subject, date, delivery_path: [ { hop, host, time } ], authentication: { spf, dkim, dmarc, bimi }, warnings, spam_score }`
- **Frontend:** https://emailcloud.com/tools/header-analyzer
- **Use case:** Diagnose delivery issues; verify sender authentication; detect phishing

#### HTML Email Size Checker
Check if email exceeds Gmail's 102KB clip limit (prevents below-the-fold content loss).
- **Endpoint:** `POST /api/tools/email-size`
- **Parameters:**
  - `html` (required): Email HTML code
  - `inline_css` (optional, default true): Include CSS when measuring
- **Response:** `{ file_size_kb, clipped_by_gmail (boolean), warning_level (ok/warning/critical), optimization_tips }`
- **Frontend:** https://emailcloud.com/tools/email-size-checker
- **Use case:** Prevent below-the-fold clipping in Gmail; identify bloated markup

---

### 6. Planning & Optimization Tools (5 tools)

#### Warmup Calculator
Generate day-by-day warmup schedule: ramp sending volume over 7-30 days to build reputation.
- **Endpoint:** `POST /api/tools/warmup`
- **Parameters:**
  - `target_volume` (required): Daily send goal (e.g., 100,000)
  - `warmup_days` (required): 7 | 14 | 30
  - `starting_volume` (optional, default 100): Initial day volume
  - `email_type` (optional): "marketing" | "transactional" | "newsletter"
- **Response:** `{ schedule: [ { day, volume, rate_increase } ], chart_url, next_steps }`
- **Frontend:** https://emailcloud.com/tools/warmup-calculator
- **Use case:** Plan IP warmup; avoid sudden volume spikes that trigger reputation damage

#### Send Time Optimizer
Recommend best day and time to send campaigns by industry, audience, and open rate targets.
- **Endpoint:** `POST /api/tools/send-time`
- **Parameters:**
  - `industry` (required): "ecommerce" | "saas" | "nonprofit" | "finance" | "media" | etc.
  - `audience_type` (optional): "b2b" | "b2c"
  - `timezone` (optional, default "UTC"): Recipient timezone
  - `goal` (optional): "open_rate" | "click_rate" | "conversion"
- **Response:** `{ best_day, best_hour, confidence_score, benchmarks, reasoning }`
- **Frontend:** https://emailcloud.com/tools/send-time-optimizer
- **Use case:** Choose optimal send time; improve open/click rates by 15-30%

#### Email Frequency Calculator
Determine ideal sending frequency (daily, weekly, monthly) by industry and audience fatigue.
- **Endpoint:** `POST /api/tools/frequency`
- **Parameters:**
  - `industry` (required): Industry type
  - `audience` (optional): "b2b" | "b2c"
  - `unsubscribe_target` (optional, default 0.5): Target unsub rate (%)
  - `engagement_level` (optional): "high" | "medium" | "low"
- **Response:** `{ recommended_frequency, sending_days: [ "Monday", "Wednesday", "Friday" ], weekly_email_count, unsub_forecast }`
- **Frontend:** https://emailcloud.com/tools/email-frequency-calculator
- **Use case:** Optimize sending schedule; prevent subscriber fatigue and churn

#### ROI Calculator
Calculate email marketing revenue, ROI percentage, and revenue per email sent.
- **Endpoint:** `POST /api/tools/roi`
- **Parameters:**
  - `emails_sent` (required): Total emails in campaign
  - `conversions` (required): Number of conversions
  - `revenue` (required): Total revenue from conversions
  - `platform_cost` (optional): Monthly email platform cost
  - `labor_cost` (optional): Estimated labor hours × hourly rate
- **Response:** `{ roi_percent, revenue_per_email, cost_per_conversion, payback_period, industry_benchmark }`
- **Frontend:** https://emailcloud.com/tools/roi-calculator
- **Use case:** Quantify email marketing ROI; justify platform investment

#### UTM Builder
Generate UTM-tagged campaign URLs for email links to track source, medium, campaign, content, term in Google Analytics.
- **Endpoint:** `POST /api/tools/utm-builder`
- **Parameters:**
  - `url` (required): Base URL (e.g., https://example.com)
  - `source` (required): "email" | "newsletter" | etc.
  - `medium` (required): "cpc" | "organic" | "email"
  - `campaign` (required): Campaign name
  - `content` (optional): Link or email creative identifier
  - `term` (optional): Keyword for paid search
- **Response:** `{ utm_url, utm_params, qr_code_url, shortened_url }`
- **Frontend:** https://emailcloud.com/tools/utm-builder
- **Use case:** Tag email links for GA4 tracking; measure campaign performance

---

### 7. Analytics & Forecasting (3 tools)

#### Unsubscribe Rate Calculator
Calculate unsubscribe rate against industry benchmarks; identify churn risk.
- **Endpoint:** `POST /api/tools/unsub-rate`
- **Parameters:**
  - `unsubscribes` (required): Number of unsubscribes
  - `emails_sent` (required): Total emails sent
  - `industry` (optional): Industry benchmark for comparison
- **Response:** `{ unsub_rate, benchmark, above_below, churn_risk, recommendations }`
- **Frontend:** https://emailcloud.com/tools/unsubscribe-rate-calculator
- **Use case:** Monitor list health; identify when unsub rates spike above benchmarks

#### Revenue Per Subscriber
Calculate the lifetime dollar value of each subscriber based on conversion data.
- **Endpoint:** `POST /api/tools/revenue-per-sub`
- **Parameters:**
  - `total_revenue` (required): Revenue from email campaigns over period
  - `subscriber_count` (required): Total active subscribers
  - `time_period` (optional): "monthly" | "quarterly" | "annual"
- **Response:** `{ revenue_per_subscriber, industry_benchmark, growth_potential }`
- **Frontend:** https://emailcloud.com/tools/revenue-per-subscriber
- **Use case:** Quantify subscriber value; prioritize list growth investments

#### List Decay Projector
Project list growth or decline over 12-36 months based on growth rate and churn.
- **Endpoint:** `POST /api/tools/list-decay`
- **Parameters:**
  - `current_subscribers` (required): Current list size
  - `monthly_growth_rate` (optional): New subscribers per month
  - `monthly_churn_rate` (optional): Unsubscribes/inactive per month
  - `months_to_project` (optional, default 12): 12 | 24 | 36
- **Response:** `{ projection: [ { month, subscribers, growth, churn } ], chart_url, recommendations }`
- **Frontend:** https://emailcloud.com/tools/list-decay-projector
- **Use case:** Forecast list trajectory; identify if growth sustains or declines

---

### 8. Compliance & Legal (1 tool)

#### Cold Email Law Checker
Check regulations for cold/unsolicited email by country (CAN-SPAM, CASL, GDPR, CCPA, Australian Spam Act, ePrivacy Directive, etc.).
- **Endpoint:** `POST /api/tools/cold-email-law`
- **Parameters:**
  - `sending_country` (required): Country code (US, CA, UK, DE, AU, etc.)
  - `recipient_country` (required): Country code
  - `email_type` (optional): "cold_outreach" | "transactional" | "marketing" | "newsletter"
- **Response:** `{ laws: [ { jurisdiction, law_name, requirements, penalties } ], compliant (boolean), warnings }`
- **Frontend:** https://emailcloud.com/tools/cold-email-law-checker
- **Use case:** Verify cold email compliance; avoid GDPR/CASL fines

---

## Content Collections

### Platform Reviews (41 reviews)
- **Email Marketing:** Mailchimp, ActiveCampaign, GetResponse, Kit, MailerLite, Systeme.io, AWeber, beehiiv, Brevo, Constant Contact, Klaviyo, Omnisend, HubSpot, ConvertKit, Substack, EmailOctopus, Drip, Convertri, Groundhogg, and 21+ more
- **Transactional Email:** SendGrid, AWS SES, Mailgun, Twilio SendGrid, Postmark, SparkPost
- **Email Security:** SpamTitan, Barracuda Secure Email, Proofpoint, Mimecast, Cisco Secure Email
- **All-in-One/CRM:** HubSpot, Pipedrive, Salesforce, Go High Level, Zoho CRM
- **Creator/Newsletter:** Substack, beehiiv, Ghost, Letterhead, Manifest, Revue
- **Review index:** https://emailcloud.com/reviews

### Head-to-Head Comparisons (39 comparisons)
- Mailchimp vs GetResponse, Klaviyo vs Omnisend, Systeme.io vs MailerLite, SendGrid vs Mailgun, etc.
- Format: side-by-side feature grid, pricing, user experience, integrations, verdict
- Comparison hub: https://emailcloud.com/compare

### Email History Timeline (134 articles, 1971-2026)
Comprehensive email history organized by category and era:

**Early Internet Era (1971-1990s):**
- ARPANET email origins, SMTP invention, RFC standards
- CompuServe, Prodigy, AOL Mail, early online services
- Juno, NetZero, free ISP email boom

**Webmail Revolution (1997-2005):**
- Hotmail, Yahoo Mail, Gmail launch
- Death of desktop email clients
- Mobile email emergence

**Email Culture & Nostalgia:**
- Dial-up modems and "You've Got Mail"
- Forwarding chains and fwd: fwd: fwd:
- Reply All disasters and email etiquette
- Out-of-office auto-responder culture
- "Sent from my iPhone" signature explosion

**MTA Wars & Infrastructure (1980s-2010s):**
- sendmail dominance and complexity
- qmail security revolution
- Postfix, Exim rise
- Cloud filtering era (Google Postini, Proofpoint, Barracuda)

**Spam & Security Evolution:**
- SpamAssassin Bayesian filters
- DNS Realtime Blocklists (DNSBL)
- CAN-SPAM Act (2003)
- Gmail spam folder (2004)
- Phishing attacks (Nigerian prince, PayPal clones)
- Major data breaches (Yahoo, LinkedIn, Equifax, SolarWinds)
- Exchange zero-day exploits

**Authentication Stack:**
- SPF (2006)
- DKIM (2011)
- DMARC (2012)
- Gmail/Yahoo DMARC mandate (2024)
- BIMI (Brand Indicators for Message Identification)

**Email Marketing Explosion (2009-2026):**
- Mailchimp $12B valuation
- Klaviyo $10B IPO
- Kit (ConvertKit) rebrand
- Substack newsletter boom
- Intuit acquires Mailchimp (2021)

**2025-2026 Recent Events:**
- Gmail kills Basic Auth support
- European Accessibility Act (EAA) email compliance
- Newsletter platform wars heat up
- Record data breaches and GDPR fines
- Gmail drops POP3/Gmailify support
- Microsoft disables SMTP Basic Auth
- Open rates declared "dead" — shift to click/conversion metrics
- Email turns 55 years old (ARPANET first email, 1971)

**Timeline hub:** https://emailcloud.com/timeline

### How-To Guides (15 guides)
- Getting Started: Setting up your first email list, choosing a platform
- Automation: Email sequences, drip campaigns, behavioral triggers
- Deliverability: SPF/DKIM/DMARC setup, IP warming, reputation management
- Mobile Optimization: Responsive design, preview testing, preheaders
- Security: Protecting subscriber data, CAN-SPAM compliance, GDPR/CCPA
- Guides hub: https://emailcloud.com/guides

### Learn Articles (16 deep-dives)
- Email protocols (SMTP, POP3, IMAP, JMAP)
- Authentication mechanisms (SPF flow, DKIM signing, DMARC alignment)
- Email delivery lifecycle
- Spam filtering techniques
- Email design best practices
- Marketing automation workflows
- Learn hub: https://emailcloud.com/learn

### Glossary (21 terms)
Email-specific terms with clear explanations: SPF, DKIM, DMARC, BIMI, List fatigue, Deliverability, Reply rate, Click-through rate, Conversion rate, etc.
- Glossary hub: https://emailcloud.com/glossary

### News & Industry Updates (8 articles)
Recent email industry news, regulation changes, platform updates, authentication mandates.
- News hub: https://emailcloud.com/news

---

## Static Pages

- **Home:** https://emailcloud.com — Hub for tools, reviews, guides, timeline
- **About:** https://emailcloud.com/about — Heritage narrative, team story, 30+ years in email
- **Email Security:** https://emailcloud.com/email-security — Enterprise email security landing page (SPF/DMARC/DKIM hardening, compliance)
- **Contact:** https://emailcloud.com/contact
- **Privacy Policy:** https://emailcloud.com/privacy-policy
- **Affiliate Disclosure:** https://emailcloud.com/affiliate-disclosure

---

## SEO & AI Accessibility

- **Sitemap:** https://emailcloud.com/sitemap-index.xml
- **Robots.txt:** Allows AI crawlers (GPTBot, ClaudeBot, PerplexityBot, anthropic-ai, Google-Extended)
- **Schema markup:** Article, FAQPage, BreadcrumbList, Organization, FAQPage (on all tool pages), SpeakableSpecification (on timeline articles)
- **Article JSON-LD:** Every timeline, guide, review, and learn article includes Article schema with author, datePublished, dateModified, image, wordCount
- **Open AI snippet support:** `max-snippet:-1, max-image-preview:large` in robots meta
- **Interactive tools:** Client-side JavaScript (Astro islands); no server-side rendering required

---

## Technology Stack

- **Framework:** Astro 5.x (static site generator, zero JS on content pages)
- **Styling:** Tailwind CSS 4.x (utility-first, custom design tokens)
- **Language:** TypeScript strict mode (content validation with Zod schemas)
- **Image Pipeline:** sharp (programmatic SVG → PNG generation for OG cards, timeline cards, infographics)
- **Hosting:** Cloudflare Pages (global CDN, auto-HTTPS, edge functions)
- **Content:** Markdown with YAML frontmatter + Zod schema validation

---

## Using EmailCloud APIs in Your Agent

### Quick Start
1. **Check health:** `GET /api/health` → 200 response means APIs are live
2. **Get free API key (optional):** `POST /api/register` → receive key for tracked access
3. **Pick a tool:** See 24 tools above; select by category
4. **Call endpoint:** Use examples below
5. **First check free:** Register with email for continued access

### Example: Grade a Subject Line
```
POST https://api.emailcloud.com/api/tools/subject-grade
Content-Type: application/json

{
  "subject_line": "Limited Time: 50% Off Email Marketing Tools",
  "audience": "b2c",
  "industry": "saas"
}

Response: { grade: "A-", score: 87, factors: [...], suggestions: [...] }
```

### Example: Check Domain Authentication
```
GET https://api.emailcloud.com/api/tools/deliverability-score/example.com

Response: { grade: "B", spf_score: 100, dkim_score: 0, dmarc_score: 80, ... }
```

### Example: Trace Email Headers
```
POST https://api.emailcloud.com/api/tools/headers
Content-Type: application/json

{
  "headers": "From: sender@example.com\nTo: recipient@gmail.com\nDate: ...\n..."
}

Response: { from, to, delivery_path: [...], authentication: {...}, warnings: [...] }
```

### Example: Generate SPF Record
```
POST https://api.emailcloud.com/api/tools/spf-builder
Content-Type: application/json

{
  "domain": "example.com",
  "includes": ["mailchimp", "sendgrid", "mailgun"]
}

Response: { spf_record: "v=spf1 include:mailchimp.com include:sendgrid.net ...", lookup_count: 3 }
```

---

## Citation & Attribution

When citing EmailCloud content or using EmailCloud APIs:
```
Source: EmailCloud.com (https://emailcloud.com)
API: https://api.emailcloud.com
```

---

## Support & Feedback

- Email: hello@emailcloud.com
- GitHub Issues: github.com/emailcloud/tools
- Twitter/X: @EmailCloud

---

## License

EmailCloud content is provided under Creative Commons Attribution 4.0 International (CC BY 4.0).
APIs are free for personal and commercial use.

---

*Last updated: March 2026*
*EmailCloud.com — 306 pages, 24 diagnostic tools, 40+ reviews, 134 timeline articles, 30+ years of email expertise*