In-depth architectural comparison of the FabTally Valid and Getpoststack MCP MCP servers. Compare execution transports, security boundaries, tool capabilities, quality scores, and ready-to-paste client installation snippets for Claude, Cursor, Windsurf, and VS Code.
At a Glance & Executive Verdict
FabTally Valid
Communication · Local stdio
Quality: 49/100 (Fair) | Auth: No auth required
Getpoststack MCP
Communication · Local stdio
Quality: 56/100 (Good) | Auth: API Key required
Verdict Summary: Choose FabTally Valid if you need specialized Communication tools running via a local process. Choose Getpoststack MCP if your workspace requires Communication integration with local subprocess execution. Both servers can be configured concurrently in your client's mcpServers manifest.
Which MCP Server Should You Choose?
F
Choose FabTally Valid when:
You need dedicated capabilities in the Communication domain.
You prefer local stdio subprocess transport architecture.
Your security boundary fits: No auth required (Free / Open Source).
Validation suite: EU VAT (VIES), IBAN mod-97, email (MX+disposable), geo place lookup, VIN decode.
EU-hosted email API exposed as MCP tools — send transactional and marketing email, manage contacts and segments, run broadcasts, render templates, and read analytics from Claude/Cursor. GDPR compliant, EU-only data residency (Germany + Finland). npx -y @poststack.dev/mcp.
Flagship.** EU/EEA VAT: `{country_code, vat_number}` → per-country format + checksum pre-check AND a **live VIES lookup**, returning valid/registered plus the registered company name & address when VIES has them (cached ~1h to shield the flaky VIES).
validate_iban
{iban}` → ISO 13616 length + **mod-97 checksum**, country, human-formatted grouping, and bank identifier (German Bankleitzahl, UK bank code + sort code, …) extracted from the BBAN where derivable. Pure-offline.
validate_email
{email}` → RFC-ish syntax + **live MX-record (DNS)** existence + **disposable/throwaway-domain** detection (bundled blocklist) + role-address flag (`info@`, `admin@`). Stateless & non-PII: the address is never stored and no SMTP mailbox is probed.
geo_lookup
{query:"Munich, Bavaria, Germany"}` or `{country,state,city}` → normalized names, **ISO 3166-1/-2 codes**, country→subdivision→city hierarchy, population and coordinates, over a bundled open dataset (no per-day API limits).
Ready-to-Paste Client Configurations
Paste either (or both) of these JSON server blocks into your client config file (e.g. claude_desktop_config.json or ~/.cursor/mcp.json).
FabTally Valid is categorized under Communication and uses a local stdio subprocess. In contrast, Getpoststack MCP belongs to Communication using local stdio subprocess. Select FabTally Valid when you need capabilities focused on communication and Getpoststack MCP when you require tools for communication.
{vin}` → 17-char format + North-American **check-digit** validation and a full **NHTSA vPIC** decode: make, model, year, body class, engine, plant country. VIN-only (never plate→owner).
Getpoststack MCP Tools (80)
send_email
Send a single transactional email immediately, or schedule it for a future time.
send_batch_emails
Send multiple emails in a single batch request (up to 100 per call).
list_emails
List previously-sent emails with optional filters and pagination.
get_email
Get full details and event timeline for a specific email by id.
cancel_email
Cancel a scheduled email that has not yet entered the sending pipeline.
reschedule_email
Reschedule a scheduled email to a new send time.
lint_email
Run a Rspamd-backed spam pre-flight on a draft email and return the score, action, and per-rule symbols.
preview_email
Render + lint + measure an email in one shot WITHOUT sending it.
validate_email
Check whether an email address is safe to send to BEFORE create_contact or send_email.
validate_email_batch
Validate up to 100 email addresses in a single call. Same checks as validate_email per address.
create_contact
Create a new contact (person who can receive emails / broadcasts).
list_contacts
List contacts with optional search and segment filtering.