{"passport":{"unfragile":{"@version":"1.0","version":"2026-05","artifact":{"id":"awesome-mailsandbox","slug":"mailsandbox","name":"MailSandbox","type":"mcp","url":"https://github.com/btafoya/mailsandbox","page_url":"https://unfragile.ai/mailsandbox","categories":["mcp-servers"],"tags":[],"pricing":{"model":"open_source","free":true,"starting_price":null},"status":"active","verified":false},"capabilities":[{"id":"awesome-mailsandbox__cap_0","uri":"capability://automation.workflow.smtp.server.with.email.interception.and.storage","name":"smtp server with email interception and storage","description":"Implements a full SMTP server that intercepts outbound emails from applications without requiring code changes. Emails are parsed, stored in-memory or persistent storage, and indexed for retrieval. Uses zero external dependencies for the SMTP protocol implementation, enabling lightweight deployment in development and testing environments.","intents":["I need to test email sending in my application without hitting real mail servers","I want to inspect email headers, body, and attachments during development","I need to verify email content programmatically in integration tests"],"best_for":["backend developers testing email workflows","QA engineers validating email functionality","CI/CD pipelines requiring email testing without external services"],"limitations":["SMTP server runs on localhost only by default — not suitable for multi-machine testing without network configuration","In-memory storage mode loses emails on restart — requires persistent backend for long-term retention","No built-in rate limiting or quota enforcement — can consume unbounded memory if application sends thousands of emails"],"requires":["Application configured to send SMTP to localhost:1025 (or custom port)","No firewall blocking SMTP port","Sufficient RAM for email storage (varies by volume and attachment sizes)"],"input_types":["SMTP protocol streams","Email messages with headers, body, and MIME attachments"],"output_types":["Parsed email objects with metadata","Raw MIME content","Attachment files"],"categories":["automation-workflow","testing-infrastructure"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_1","uri":"capability://automation.workflow.web.ui.for.email.inspection.and.debugging","name":"web ui for email inspection and debugging","description":"Provides a browser-based dashboard for viewing intercepted emails with full MIME parsing, attachment preview, and raw message inspection. Built with embedded web server that serves HTML/CSS/JavaScript frontend without external web framework dependencies. Supports real-time email list updates and detailed message inspection with syntax highlighting for headers and body content.","intents":["I want to visually inspect emails sent by my application during development","I need to download attachments from test emails to verify they're generated correctly","I want to see raw MIME headers to debug email delivery issues"],"best_for":["developers debugging email templates and content","QA teams manually verifying email output before release","product managers reviewing email designs and copy"],"limitations":["Web UI is read-only — cannot resend or modify emails from the interface","No multi-user authentication — assumes single developer or trusted team access","Attachment preview limited to common formats (images, PDFs, text) — binary attachments show hex dump only"],"requires":["Web browser with JavaScript support (modern Chrome, Firefox, Safari, Edge)","Network access to MailSandbox web server (default localhost:8025)","No browser extensions blocking local requests"],"input_types":["Parsed email objects from SMTP server"],"output_types":["HTML rendered email preview","Raw MIME source code","Downloadable attachments","Email metadata (sender, recipients, timestamp)"],"categories":["automation-workflow","developer-tools"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_2","uri":"capability://tool.use.integration.postmark.api.emulation.for.email.sending","name":"postmark api emulation for email sending","description":"Implements Postmark-compatible REST API endpoints that accept email submission requests in Postmark format and route them to the internal SMTP server. Allows applications using Postmark SDK to send emails to MailSandbox without code changes. Supports Postmark request/response schemas including template variables, metadata, and delivery tracking.","intents":["I'm using Postmark SDK in my app and want to test locally without hitting Postmark's API","I need to switch between Postmark production and MailSandbox testing with minimal code changes","I want to verify Postmark API request formatting before deploying to production"],"best_for":["teams using Postmark for email delivery in production","developers integrating Postmark SDKs (Node.js, Python, Ruby, etc.)","CI/CD pipelines that need to mock Postmark API calls"],"limitations":["Not all Postmark API features are emulated — advanced features like bounce handling, suppression lists, and webhook delivery may be stubbed or missing","API responses match Postmark format but don't implement actual delivery tracking or bounce processing","Requires application to point Postmark API endpoint to MailSandbox URL — not transparent to existing Postmark client libraries"],"requires":["Postmark API client library (any language with Postmark SDK support)","Application configured to use custom API endpoint pointing to MailSandbox (http://localhost:3000 or configured URL)","Postmark API key (can be any string in test mode)"],"input_types":["HTTP POST requests in Postmark API format","JSON payloads with email metadata, templates, and variables"],"output_types":["Postmark API response JSON with message ID and status","Stored email in internal system"],"categories":["tool-use-integration","testing-infrastructure"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_3","uri":"capability://tool.use.integration.mcp.server.for.ai.assisted.email.debugging","name":"mcp server for ai-assisted email debugging","description":"Exposes MailSandbox functionality as an MCP (Model Context Protocol) server, allowing AI agents and LLM-powered tools to query, search, and analyze intercepted emails programmatically. Implements MCP resource and tool endpoints for listing emails, retrieving message content, searching by recipient/subject, and analyzing email structure. Enables Claude and other AI models to understand email testing state and assist with debugging email workflows.","intents":["I want Claude to analyze why my test emails aren't being sent correctly","I need an AI agent to search through intercepted emails and extract specific data","I want to use an LLM to generate test cases based on actual email output from my application"],"best_for":["developers using Claude or other LLM-powered IDEs (Cursor, Windsurf)","AI agent builders integrating email testing into automated workflows","teams building LLM-assisted debugging tools for email systems"],"limitations":["MCP server requires compatible client (Claude, Cursor, or custom MCP client) — not usable with standard HTTP clients","Email context sent to LLM may expose sensitive data (customer emails, PII) — requires careful prompt engineering and data filtering","MCP protocol overhead adds latency compared to direct API calls — not suitable for real-time high-frequency queries"],"requires":["MCP-compatible client (Claude with MCP support, Cursor IDE, or custom MCP client implementation)","MailSandbox running with MCP server enabled","Network connectivity between MCP client and MailSandbox MCP server"],"input_types":["MCP tool calls with parameters (search queries, email IDs, filters)","Natural language requests from LLM"],"output_types":["Email metadata and content as structured data","Search results with matching emails","Analysis summaries generated by AI"],"categories":["tool-use-integration","planning-reasoning"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_4","uri":"capability://search.retrieval.email.search.and.filtering.with.metadata.indexing","name":"email search and filtering with metadata indexing","description":"Indexes intercepted emails by sender, recipient, subject, timestamp, and custom metadata tags. Provides search API endpoints that support filtering by multiple criteria (e.g., 'emails from user@example.com sent after 2024-01-01'). Uses in-memory indexing for fast queries without external search infrastructure. Supports regex and substring matching on email content.","intents":["I need to find all emails sent to a specific user during a test run","I want to verify that emails with a specific subject line were generated","I need to filter emails by timestamp to test batch sending workflows"],"best_for":["test automation engineers writing email assertions","developers debugging email delivery issues by filtering large email volumes","QA teams verifying email workflows with complex recipient lists"],"limitations":["In-memory indexing means search performance degrades with large email volumes (>10,000 emails) — no pagination or lazy loading","Regex search on email body is not optimized — full-text search would require external Elasticsearch or similar","Index is not persisted across restarts — search results only available for emails received in current session"],"requires":["MailSandbox running with email storage enabled","HTTP client or SDK to query search API","Knowledge of email metadata fields available for filtering"],"input_types":["Search query parameters (sender, recipient, subject, date range, custom filters)","Regex patterns for content matching"],"output_types":["Filtered list of email objects","Email count matching criteria","Metadata summaries"],"categories":["search-retrieval","data-processing-analysis"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_5","uri":"capability://data.processing.analysis.email.attachment.extraction.and.preview","name":"email attachment extraction and preview","description":"Automatically extracts and stores MIME attachments from intercepted emails with support for multiple content types (images, PDFs, text, binary). Provides endpoints to list attachments for a given email, download raw attachment files, and generate previews for supported formats. Uses MIME parsing to identify attachment boundaries and content-type headers without external libraries.","intents":["I need to verify that my application generates PDF invoices correctly in email attachments","I want to download and inspect image attachments sent by my email templates","I need to programmatically extract attachment metadata (filename, size, MIME type) for testing"],"best_for":["developers testing email templates with attachments","QA teams verifying document generation in email workflows","automation engineers writing assertions on attachment content"],"limitations":["Preview generation limited to common formats (JPEG, PNG, PDF, plain text) — binary or proprietary formats show hex dump only","Large attachments (>100MB) may cause memory issues in in-memory storage mode — no streaming download support","No virus scanning or malware detection — assumes test environment is isolated"],"requires":["Emails with MIME-encoded attachments","Sufficient disk/memory space for attachment storage","HTTP client to download attachments"],"input_types":["MIME-encoded email messages with attachment parts"],"output_types":["Raw attachment files (binary or text)","Attachment metadata (filename, size, MIME type, encoding)","Preview images or text content"],"categories":["data-processing-analysis","automation-workflow"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_6","uri":"capability://automation.workflow.email.delivery.simulation.and.status.tracking","name":"email delivery simulation and status tracking","description":"Tracks email state through a simulated delivery pipeline (received, processing, delivered, failed) with configurable delays and failure injection. Allows tests to simulate delivery failures, bounces, and delays without modifying application code. Provides API to query delivery status and simulate webhook callbacks for delivery events.","intents":["I want to test how my application handles email delivery failures","I need to simulate delayed email delivery to test timeout handling","I want to inject bounce events to verify my application's bounce handling logic"],"best_for":["developers testing email error handling and retry logic","QA teams validating resilience to email delivery failures","teams building email delivery monitoring systems"],"limitations":["Delivery simulation is basic — doesn't model real SMTP rejection codes or bounce types (hard bounce vs soft bounce)","Webhook callbacks are not guaranteed delivery — no retry mechanism if application is temporarily unavailable","Failure injection is deterministic — cannot simulate probabilistic failures or cascading failures across multiple emails"],"requires":["Application configured to handle delivery status callbacks","Webhook endpoint in application to receive delivery events","MailSandbox configured with callback URL"],"input_types":["Configuration parameters for delivery delay and failure rate","Email IDs to simulate delivery events for"],"output_types":["Delivery status updates (received, processing, delivered, failed)","Webhook POST requests to application","Status query responses"],"categories":["automation-workflow","testing-infrastructure"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_7","uri":"capability://data.processing.analysis.persistent.email.storage.with.multiple.backend.options","name":"persistent email storage with multiple backend options","description":"Supports multiple storage backends (in-memory, SQLite, PostgreSQL) for persisting intercepted emails across restarts. Uses pluggable storage interface to abstract backend implementation. Enables long-running test environments and historical email analysis without data loss. Automatically handles schema creation and migrations.","intents":["I need emails to persist across MailSandbox restarts during development","I want to store test emails in a database for historical analysis","I need to run MailSandbox in a persistent environment for integration testing"],"best_for":["teams running MailSandbox in persistent development environments","CI/CD pipelines that need email history across test runs","developers analyzing email patterns over time"],"limitations":["SQLite backend suitable only for single-process access — concurrent writes may cause locking issues","PostgreSQL backend requires external database setup and network connectivity — adds deployment complexity","No built-in data retention policies — emails accumulate indefinitely without manual cleanup"],"requires":["For SQLite: file system write access to store database file","For PostgreSQL: PostgreSQL 12+ server, network connectivity, database credentials","Sufficient disk space for email storage (varies by volume and attachment sizes)"],"input_types":["Email objects from SMTP server","Storage backend configuration"],"output_types":["Persisted email records in database","Query results from storage backend"],"categories":["data-processing-analysis","automation-workflow"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_8","uri":"capability://tool.use.integration.rest.api.for.programmatic.email.access","name":"rest api for programmatic email access","description":"Exposes comprehensive REST API endpoints for querying emails, retrieving message content, downloading attachments, and managing email state. Supports JSON request/response format with standard HTTP status codes. Enables integration with test frameworks, CI/CD pipelines, and custom tooling without requiring direct SMTP or web UI access.","intents":["I want to write test assertions on email content using my test framework's HTTP client","I need to integrate email testing into my CI/CD pipeline with REST API calls","I want to build custom tooling that queries MailSandbox for email data"],"best_for":["test automation engineers writing email assertions in test frameworks","CI/CD pipeline builders integrating email testing","developers building custom email testing tools"],"limitations":["REST API is synchronous — no streaming or long-polling for real-time email updates","No built-in rate limiting — high-frequency API calls may impact performance","API responses include full email content — large emails or attachments may cause slow responses"],"requires":["HTTP client library in test framework or CI/CD tool","MailSandbox running with REST API enabled","Network access to MailSandbox API endpoint"],"input_types":["HTTP GET/POST requests with query parameters or JSON bodies","Email IDs, search filters, or pagination parameters"],"output_types":["JSON responses with email data","Binary attachment files","HTTP status codes indicating success/failure"],"categories":["tool-use-integration","automation-workflow"],"confidence":0.5,"matches":0,"success_rate":0},{"id":"awesome-mailsandbox__cap_9","uri":"capability://text.generation.language.email.template.rendering.and.preview","name":"email template rendering and preview","description":"Provides endpoints to render email templates with variable substitution and preview HTML/plain-text output. Supports common template syntaxes (Handlebars, Liquid, simple variable interpolation). Allows testing email template logic without sending through application code. Includes HTML sanitization to prevent XSS in preview.","intents":["I want to preview how my email template renders with different variable values","I need to test email template logic without running my full application","I want to verify HTML email rendering before sending to real users"],"best_for":["email template developers testing template logic","designers previewing email layouts with test data","developers validating template variable substitution"],"limitations":["Template rendering is basic — doesn't support complex logic like loops or conditionals in all template syntaxes","HTML preview is browser-based — rendering may differ from actual email clients (Outlook, Gmail, etc.)","No CSS inlining — styles in