How to Monitor Exim with Xitoring

Overview

Exim is a powerful Mail Transfer Agent used across countless Linux systems to manage email routing, delivery, and security. Monitoring Exim gives you visibility into queue health, delivery throughput, and potential security issues.

Prerequisites

A Linux server running Exim
Xitogent agent installed on the server
An active Xitoring account

Step 1 — Install Xitogent

curl -s https://xitoring.com/install.sh | sudo bash -s -- --key=YOUR_API_KEY

Step 2 — Enable the Exim Integration

sudo xitogent integrate

Select Exim from the available integrations. The agent will detect your Exim installation and start collecting metrics automatically.

Key Metrics to Monitor

Metric	Description
Mail Queue Size	Total messages waiting for delivery
Messages Delivered	Successful deliveries per interval
Messages Rejected	Connections or messages rejected by policy
Frozen Messages	Messages stuck in the queue that cannot be delivered
SMTP Connections	Active and total SMTP connections
Retry Queue	Messages scheduled for re-delivery attempts

Step 3 — Configure Triggers

Mail Queue Size (Warning) — Alert when queue depth exceeds normal levels
Frozen Messages (Critical) — Fires when messages become frozen, requiring manual intervention
Rejected Messages (Warning) — Triggers on high rejection rates that may indicate abuse or misconfiguration

Best Practices

Monitor frozen messages closely — Frozen messages won't deliver without intervention; set up critical alerts
Track queue age — Old messages in the queue indicate persistent delivery failures
Use SMTP uptime checks — Verify Exim is accepting connections on ports 25 and 587 from external locations
Review rejection logs — High rejection rates could indicate brute-force attacks or relay attempts

Troubleshooting

No metrics: Verify Exim is running with systemctl status exim4 (Debian/Ubuntu) or systemctl status exim (RHEL/CentOS)
Queue growing: Run exim -bp to inspect the queue and exim -Mvl <message-id> to view message logs
Frozen messages: Use exim -Mg <message-id> to thaw or exim -Mrm <message-id> to remove