MCP server · Analytics

PostSleuth MCP server

Let your AI look at a Postfix mail queue and logs to explain why email is not being delivered.

Analytics For it and development For operations Monitoring

PostSleuth is a helper for people who run a Postfix mail server and keep seeing messages stuck in the queue. It reads the queue, the mail log and some DNS records, then groups the stuck messages by the reason they are stuck and suggests what to do next. It is handy for sysadmins and anyone who has to answer the question: why is this email not going out?

What is an MCP server? The 30-second version

On its own, your AI can only chat. An MCP server is a small helper program that gives your AI a new skill or a connection to a service, and here that service is your Postfix mail server. Once connected, the AI can ask PostSleuth to look at the queue, the logs and DNS, and then explain the results to you in plain words. You stay in the chat; PostSleuth does the digging on the server.

What this MCP server does

You ask your AI something like why mail to Gmail is bouncing. The AI passes that question to PostSleuth. PostSleuth runs commands like postqueue and reads your mail log, then groups the stuck messages by their deferral reason. It also checks SPF, DKIM, DMARC and PTR records for the domains involved. The AI then tells you what is wrong and what to try next, all inside the chat.

What you can do with it

See the whole Postfix queue grouped by why messages are stuck
Check qshape to find which sender or domain is filling the queue
Look at deferral trends over time for a domain like gmail.com
Trace one email address from start to finish in the logs
Check SPF, DKIM, DMARC and PTR records for a domain
Look up a provider reply code and get ordered recovery steps
Requeue, flush, hold or delete messages only if you turn on the opt-in flag

Try asking your AI

“Why are messages to outlook.com stuck in the Postfix queue?”
“Show me the queue grouped by deferral reason.”
“Trace bob@example.org through the mail log.”
“What does Gmail 4.7.28 mean and what should I do?”

What it gives back to you

You get back plain answers in the chat: a grouped list of stuck messages with reasons, counts and affected domains. For a trace you get the story of one message, step by step. For DNS checks you get pass or fail results for SPF, DKIM, DMARC and PTR. If you allowed changes, it also tells you which messages it requeued, flushed, held or deleted.

Before you start

What you need

A Postfix mail server you can run commands on
Access to the mail log and the postqueue command
The postsleuth program installed (Go install or a release binary)

Good to know

By default it is read-only, but if you start it with --allow-mutations it can requeue, flush, hold or delete messages, and each of those calls still needs confirm: true.

Install it with your AI

Add PostSleuth MCP server to your AI, no technical skills needed

You don't install anything by hand. You copy one prompt, paste it into an AI that can work on your computer, and it checks, installs and connects the server for you, asking you when it needs something.

Sign in to get the install prompt

Members get a ready-made prompt that lets the Claude desktop app check PostSleuth MCP server, install it and connect it for them, step by step. You don't need any technical skills: you copy, paste and answer a few questions. Your connected AI can also find and install any of the 4,609 MCP servers here for you.