Email Subject Line Optimizer Connector for AI agents.
3 live capabilities
Ensure your email subject lines land in the inbox and get opened by your customers.
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Why people use Email Subject Line Optimizer
Email Subject Line Optimizer: Stop losing opens to spam filters and mobile truncation
With this Connector, you just feed your draft to your agent. It instantly scans for deliverability risks, predicts your engagement score, and shows you exactly where your text will cut off on a mobile screen. You get a full audit in seconds instead of an afternoon of manual checks.
What Vinkius changes
You get a data-backed preview of how your emails will perform before you hit send.
Use it from Claude, ChatGPT, Cursor or another AI client you already have.
One account · 6,100+ Connectors
- Real-world use case 01
Checking high-risk sales copy
A marketing manager wants to know if 'ACT NOW - WIN A PRIZE' is too risky for a newsletter.
- Real-world use case 02
Mobile layout testing
A copywriter wants to see if their 15-word subject line fits on an iPhone.
- Real-world use case 03
Engagement scoring for A/B tests
An e-commerce owner wants to know which of five subject lines will perform best.
Complete set · 3capabilities
The complete Email Subject Line Optimizer capability set.
These are the exact actions your AI can choose when you ask it to work with Email Subject Line Optimizer.
01—03
3 capabilities in this set.
Part of 3 available through Email Subject Line Optimizer.
- 01 Capability
Analyze spam risk
Finds forbidden words and formatting patterns that trigger spam filters. Use it to clean up your copy before sending.
- 02 Capability
Estimate engagement score
Predicts open rates based on personalization, length, and emoji use. It helps you pick the best subject line.
- 03 Capability
Predict display behavior
Shows exactly how your subject line and preheader appear in different mail apps. It prevents text truncation.
Set up in minutes
One URL. Then ask Email Subject Line Optimizer to work.
Claude and ChatGPT only need the Connector URL. Copy it once, add it in settings, and use Email Subject Line Optimizer from the conversation.
Choose your client
Live previewAdvanced clients IDE · CLI
Claude · Web + desktop
Connector URL · ready to paste
Streamable HTTPhttps://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp - Step 01
Open Connectors
In Claude Web or Claude Desktop, open Settings and choose Connectors.
- Step 02
Add the URL
Choose Add custom connector, name it Email Subject Line Optimizer, and paste the URL above.
- Step 03
Turn it on in chat
Select +, open Connectors, and enable Email Subject Line Optimizer for the conversation.
ChatGPT · Web + desktop
Connector URL · ready to paste
Streamable HTTPhttps://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp - Step 01
Open MCP settings
On desktop, open Settings and MCP servers. On web, open your workspace app or connector settings.
- Step 02
Add the URL
Choose Add server with Streamable HTTP, or create a custom MCP app, then paste the Email Subject Line Optimizer URL.
- Step 03
Save and start
Save the connection and enable Email Subject Line Optimizer in your conversation. Desktop may ask you to restart once.
Cursor · IDE configuration
Advanced setup
{
"mcpServers": {
"email-subject-line-optimizer": {
"url": "https://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp"
}
}
}- Step 01
Open MCP Settings
Press Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows/Linux) → search "MCP Settings"
- Step 02
Add the server config
Paste the JSON configuration above into the mcp.json file that opens
- Step 03
Save the file
Cursor will automatically detect the new Connector
- Step 04
Start using Email Subject Line Optimizer
Open Agent mode in chat and ask: "Using Email Subject Line Optimizer, help me...". 3 tools available
VS Code Copilot · IDE configuration
Advanced setup
{
"mcpServers": {
"email-subject-line-optimizer": {
"url": "https://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp"
}
}
}- Step 01
Create MCP config
Create a .vscode/mcp.json file in your project root
- Step 02
Add the server config
Paste the JSON configuration above
- Step 03
Enable Agent mode
Open GitHub Copilot Chat and switch to Agent mode using the dropdown
- Step 04
Start using Email Subject Line Optimizer
Ask Copilot: "Using Email Subject Line Optimizer, help me...". 3 tools available
Windsurf · IDE configuration
Advanced setup
{
"mcpServers": {
"email-subject-line-optimizer": {
"url": "https://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp"
}
}
}- Step 01
Open MCP Settings
Go to Settings → MCP Configuration or press Cmd+Shift+P and search "MCP"
- Step 02
Add the server
Paste the JSON configuration above into mcp_config.json
- Step 03
Save and reload
Windsurf will detect the new server automatically
- Step 04
Start using Email Subject Line Optimizer
Open Cascade and ask: "Using Email Subject Line Optimizer, help me...". 3 tools available
Cline · IDE configuration
Advanced setup
{
"mcpServers": {
"email-subject-line-optimizer": {
"url": "https://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp"
}
}
}- Step 01
Open Cline MCP Settings
Click the Connectors icon in the Cline sidebar panel
- Step 02
Add remote server
Click "Add Connector" and paste the configuration above
- Step 03
Enable the server
Toggle the server switch to ON
- Step 04
Start using Email Subject Line Optimizer
Ask Cline: "Using Email Subject Line Optimizer, help me...". 3 tools available
Claude Code · Terminal command
Advanced setup
claude mcp add email-subject-line-optimizer --transport http "https://edge.vinkius.com/vk_preview_Y6N7kOEAtnVgLrzqqT8Bx9hVPF7rocDFnoVgxEaq/mcp"- Step 01
Install Claude Code
Run npm install -g @anthropic-ai/claude-code if not already installed
- Step 02
Add the Connector
Run the command above in your terminal
- Step 03
Verify the connection
Run claude mcp to list connected servers, or type /mcp inside a session
- Step 04
Start using Email Subject Line Optimizer
Ask Claude: "Using Email Subject Line Optimizer, show me...". 3 tools are ready
Where the request belongs
Work Email Subject Line Optimizer can move forward.
This is for email marketers and copywriters who are tired of low open rates and want to ensure their subject lines actually reach the inbox and look good on mobile.
Email Marketer
They use this to audit dozens of A/B test variations to see which ones have the highest predicted engagement score.
Copywriter
They use this to ensure their creative hooks don't get cut off on different mobile devices like iPhones or Androids.
E-commerce Owner
They use this to make sure their high-volume sales emails don't trigger spam filters and get blocked by major providers.
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Bring your own AI
Change the model, client or framework. Keep Email Subject Line Optimizer connected.
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Before you connect
Questions about Email Subject Line Optimizer.
The practical details behind the request, access and result.
Can the Email Subject Line Optimizer tell me if my email will go to spam?
Yes, it scans your subject line for specific words and formatting patterns that are known to trigger spam filters. It gives you a risk assessment so you can clean up your copy before sending.
How does this help with mobile users?
It predicts exactly where your text will get cut off on different mobile devices. You'll see the specific character count for Gmail, Outlook, and Apple Mail so you can keep your hook visible.
Can I use this for A/B testing?
Absolutely. You can run multiple subject line variations through the optimizer to see which ones get the highest predicted engagement scores before you launch your campaign.
Does it work for both Gmail and Outlook?
Yes, it evaluates how your subject line and preheader will appear across major mail clients, including Gmail, Outlook, and Apple Mail.
Is the Email Subject Line Optimizer good for cold outreach?
It's excellent for cold outreach because it helps you identify 'spammy' triggers that could get your emails blocked, while also ensuring your main hook is visible on mobile.
Does it check my preheader text too?
Yes, it evaluates both the subject line and the preheader text to ensure your full message is presented correctly and isn't cut off prematurely.
How does the spam risk detection work?
The analyze_spam_risk capability 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.
Can I see how my email will look on mobile devices?
Yes, by using the predict_display_behavior capability, you can identify exactly where your subject line and preheader text will be truncated on various clients like Gmail Mobile, Outlook Desktop, and Apple Mail iOS.
What factors influence the engagement score?
The estimate_engagement_score capability calculates a score based on character length, the presence of personalization tokens, urgency markers, and emoji usage to predict how likely users are to open your email.
One connection away
Give your agent a direct line to Email Subject Line Optimizer.
Connect Email Subject Line Optimizer once. Keep it beside 6,100+ managed Connectors when the next task needs more.
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