postbox-tools
Free email checks: 24 blacklists, spoofing/BEC grade, redirect tracing, email spam test, WHOIS.
Should I use this
Quality & Safety
Based on automated analysis of tool definitions and protocol compliance.
Context Cost
This is the approximate number of tokens consumed each time the server's tools are loaded into a model's context. Higher counts reduce the attention available for other tasks.
Install
One-Click Install
Add this to your `claude_desktop_config.json` file:
{
"mcpServers": {
"postbox-tools": {
"url": "https://mcp.postboxservices.com/mcp"
}
}
}Remote endpoints
https://mcp.postboxservices.com/mcpstreamable-httpWhat it can do
Tool inventory
Tools (8)
🟢check_blacklist(target)
Check a domain (its mail-relevant IPs) or a single IP address against 24 DNS blacklists including Spamhaus ZEN, Barracuda and SpamCop. Returns per-IP listing status. Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"target": {
"type": "string",
"description": "Domain (example.com) or IPv4 address to check"
}
},
"required": [
"target"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢check_spoofability(domain)
Grade how exposed a domain is to email spoofing and business email compromise, from its public DNS (SPF, DMARC policy strength, alignment, live lookalike domains). Returns an A-F grade with findings. Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"domain": {
"type": "string",
"description": "Domain to grade, e.g. example.com"
}
},
"required": [
"domain"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}⚪trace_redirect(url)
Follow a URL server-side through every HTTP redirect hop to its real final destination - per-hop status, IP, TLS and timing, plus phishing/deliverability flags (cross-domain jumps, https downgrades, meta/JS redirects). Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"url": {
"type": "string",
"description": "Absolute http:// or https:// URL to trace"
}
},
"required": [
"url"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟡create_mailtest
Create a disposable test address for a full email deliverability audit (score /10: SPF, DKIM, DMARC + alignment, blacklists, reverse DNS, SpamAssassin content, Gmail/Yahoo bulk-sender compliance). The USER must then send an email from the system they want to test to the returned address, after which get_mailtest_result returns the score. Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {},
"$schema": "http://json-schema.org/draft-07/schema#"
}🟡get_mailtest_result(id)
Fetch the score and breakdown of a mail test created with create_mailtest, once the user has sent their email to the disposable address.
Input Schema
{
"type": "object",
"properties": {
"id": {
"type": "string",
"description": "The test id returned by create_mailtest"
}
},
"required": [
"id"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟡analyze_eml(eml)
Run a deliverability/content analysis on a raw RFC 822 email (.eml source: full headers + body). IMPORTANT LIMITS: with no live SMTP session, SPF, blacklist and reverse-DNS cannot be verified from a file - for the authoritative score use create_mailtest instead. Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"eml": {
"type": "string",
"description": "The complete raw email source (headers + body), as exported via \"Show original\" / \"Download message\""
}
},
"required": [
"eml"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢get_domain_age(domain)
Get a domain's registration date and age (young domains have weak sending reputation). Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"domain": {
"type": "string",
"description": "Domain, e.g. example.com"
}
},
"required": [
"domain"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}⚪whois_lookup(domain)
WHOIS summary for a domain: registrar, created/updated/expires dates, nameservers, DNSSEC, status flags. Free tool by Postbox Services.
Input Schema
{
"type": "object",
"properties": {
"domain": {
"type": "string",
"description": "Domain, e.g. example.com"
}
},
"required": [
"domain"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}Community
Evidence