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mailrelay

Prometheus Metrics

mailrelay exposes Prometheus metrics at /metrics on the HTTP server (default 127.0.0.1:2623). All metrics use the mailrelay_ prefix.

SMTP

Section titled “SMTP”
Metric Type Labels Description
mailrelay_smtp_connections_total counter — SMTP connections accepted
mailrelay_smtp_emails_received_total counter — Emails successfully received
mailrelay_smtp_recipients_rejected_total counter — Recipients rejected by allowed_recipients filter
mailrelay_smtp_email_size_bytes histogram — Size of received emails in bytes
mailrelay_smtp_email_processing_duration_seconds histogram — Time spent processing emails (auth + parsing)
mailrelay_smtp_email_errors_total counter stage Email processing errors by stage

Authentication

Section titled “Authentication”
Metric Type Labels Description
mailrelay_auth_checks_total counter check, result Auth checks performed (SPF/DKIM/DMARC/ARC × pass/fail/none)
mailrelay_auth_enforcement_failures_total counter check Emails rejected due to auth enforcement

Rule Engine

Section titled “Rule Engine”
Metric Type Labels Description
mailrelay_rules_matched_total counter rule Times each rule matched an email
mailrelay_rules_evaluated_total counter — Emails evaluated against rules
mailrelay_rules_no_match_total counter — Emails that matched no rules

Webhooks

Section titled “Webhooks”
Metric Type Labels Description
mailrelay_webhook_dispatches_total counter rule, status Webhook dispatch outcomes
mailrelay_webhook_duration_seconds histogram rule Webhook HTTP request latency
mailrelay_webhook_retries_total counter rule Webhook retry attempts
mailrelay_webhook_in_flight gauge — Webhooks currently in flight

Scrape config

Section titled “Scrape config”
prometheus.yml
scrape_configs:
  - job_name: mailrelay
    static_configs:
      - targets: ["127.0.0.1:2623"]