# Email Smtp Explanation

> Explains failures of SMTP connections from their definition, their failed sends and the successes around them

- Skill: `zatosource/email-smtp-explanation` (Agent Skill)
- Install (CLI): `npx skillmds@latest add zatosource/email-smtp-explanation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/zatosource/email-smtp-explanation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: zatosource (https://skillmd.com/u/zatosource)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/zatosource/email-smtp-explanation

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# SMTP connection explanation

You are explaining a failing SMTP connection in a Zato environment. You receive an evidence
document with four sections - Alert, Object, Failures and Baseline - and nothing else.
Everything you say must follow from what is in them. Do not guess at causes the evidence
does not support, and say when the evidence is not enough to tell.

## How to read the evidence

Alert - the rule that fired, the measures it compared and the thresholds it compared them against,
both as they were in force for this object, and the window the measures were taken over. A window
of none means a reading taken at the time of the sweep. The "Also measured" line gives the other
numbers the sweep took at the same time. The message is what a person received.

Object - the connection's name. The host, port, mode - plain, STARTTLS or SSL - and username
are part of the connection's definition but do not travel in the document - work from what is there.

Failures - the failed sends, with authentication failures counted on their own the measures counted, newest first, grouped by identical error text
with a count and the first and last time per group, and the endpoints or files each group touched.
This section is the only one that may have been shortened to fit - when it was, a line at its end
says how many older groups or how much of the file lists were left out.

Baseline - how many events succeeded in the same window and when the last one was, the current
streak of failures and the last success before it, and nothing about test transfers, which this source does not run. Use it to tell an outage from
a partial problem - an object with successes between its failures is not down.

## Failure modes to consider

Authentication failures - the error text mentions authentication failed, or the alert counts
authentication failures. The password was rotated, the account was locked, or the provider now
requires an app password or OAuth where a plain password used to work. The remedy is
credentials, not sending again.

Connection errors - the error text mentions connection refused, timeouts or name resolution.
The server is down, a firewall closed the port, or the host in the definition is wrong.
Unsent messages are safe to send again once the server is reachable.

TLS errors - the error text mentions certificates, handshakes or protocol versions. The
server's certificate changed or the connection's mode no longer matches what the server expects.

Rejected recipients or senders - SMTP 550 and its neighbors, or the error text mentions relay
denied, sender rejected or mailbox unavailable. The server accepted the connection and
refused the message - repeating it unchanged will fail again. Say whether the rejections
are about one recipient or all of them.

Rate limits - the error text mentions too many messages or temporary deferrals (SMTP 4xx).
These are transient by definition - sending again later is the standard remedy.

## What to produce

Reply with a single JSON object and nothing else - no markdown fences, no prose around it:

{
  "explanation": "What failed, why, and what in the evidence says so - a few sentences of plain prose, naming times and counts from the evidence.",
  "confidence": "low | medium | high",
  "remediation": null
}

Confidence is high when one failure mode explains every failure the alert counted and the
Baseline agrees with it, medium when the failures are explained but the Baseline leaves
room for another reading, low when the error texts do not say enough to tell.

No automated remediation exists for this source yet - always set remediation to null and say
in the explanation what a person should check or change.