MCP For Claude Marketplace
Email Subject Line Optimizer

Email Subject Line Optimizer MCP Connector for Claude

A+

Analyze email subject lines for spam risk, engagement potential, and display truncation.

3 tools Official Updated Oct 1, 2026 Official Vinkius Partner
More Details Connect to Claude

Maximize your email open rates with the Email Subject Line Optimizer. This MCP server provides advanced analytical tools to evaluate your subject lines and preheader text across three critical dimensions: deliverability, engagement, and visual presentation. Use analyze_spam_risk to detect potential spam triggers like excessive punctuation or forbidden words. Utilize estimate_engagement_score to predict open rates based on length, personalization, and emoji usage. Finally, use predict_display_behavior to identify truncation points for Gmail, Outlook, and Apple Mail, ensuring your most important message is never hidden.

emailsubject-linespam-detectionopen-ratemarketing-automation

3 tools expose this connector's capabilities to your AI agent.

analyze_spam_risk

Detects vocabulary and formatting patterns that trigger spam filters

predict_display_behavior

Evaluates how the subject line and prehtml will appear across different mail clients

estimate_engagement_score

Predicts the potential for higher open rates based on engagement drivers

See how to talk to your AI agent using Email Subject Line Optimizer.

Check this subject line for spam risk: 'WIN FREE CASH NOW!!!'

Spam Risk Detected: 3 words found in the spam lexicon (FREE, CASH, NOW). Caps Ratio: 52.4%. Punctuation Alert: True due to excessive exclamation marks.

How will this subject line appear on Gmail mobile? Subject: 'Your weekly newsletter is highly anticipated!' Preheader: 'Don't miss out on the latest updates.'

Gmail Mobile Truncation Point: 32 characters. The preheader text will be visible up to the '...' mark. No redundancy detected.

Estimate the engagement score for: Subject: 'Hey {{name}}, check this out! 🚀' Preheader: 'A special gift just for you.'

Engagement Score: 85. Personalization Detected: True. Urgency Level: 2. Emoji Count: 1.

The `analyze_spam_risk` tool scans your text against a categorized lexicon of known spam triggers, including financial, urgency, and marketing-related words. It also flags formatting issues like high ALL CAPS ratios or excessive exclamation marks.

Related Connectors

LLM Response Structural Validator

LLM Response Structural Validator MCP

3 tools Official

Detect and prevent silent structural failures in LLM outputs using deterministic pattern matching.

A+ View details →
LinkedIn Broetry Structure Validator

LinkedIn Broetry Structure Validator MCP

3 tools Official

Analyze LinkedIn posts for adherence to the 'broetry' writing style using structural metrics.

A+ View details →
LinkedIn Mention and Tag Distribution Checker

LinkedIn Mention and Tag Distribution Checker MCP

4 tools Official

Quantify the strategic placement of @mentions and #hashtags in LinkedIn posts.

A+ View details →
Markdown Semantic Chunker

Markdown Semantic Chunker MCP

3 tools Official

A deterministic engine for splitting Markdown text into semantically coherent chunks based on header hierarchy and paragraph boundaries.

A+ View details →