---
title: "SMTP Monitor"
description: "The SMTP Monitor verifies that your SMTP server is reachable and responsive. This helps you detect outages of outbound mail gateways and mail delivery infrastructure before users report missing emails."
---

## How it works

- We connect to your SMTP server and validate that it responds as expected.
- If the server cannot be reached or does not respond in time, we mark the check as failed.

## Configuration

### Basic settings

- **Hostname**: Hostname only, without protocol or path.
- **Port**: Optional. Use your SMTP port (commonly 25 / 587 / 465).
- **Check interval** and **Timeout**.
- **Status**: `active`, `maintenance`, `disabled`.

### Advanced settings

Depending on your use case, advanced options (e.g. encryption/auth requirements) can be configured via the monitor settings.

### Monitoring locations

SMTP checks run from our monitoring locations. You can restrict execution using **Allowed Check Countries** (monitor-level) or by using the customer-level defaults.

### Port-only mode (no credentials)

By default (**Check Mode**: `protocol`), the monitor connects to your SMTP server and validates that it responds as expected. Set **Check Mode** to `tcp` to skip that protocol validation. The monitor only opens a bare TCP connection to `hostname:port`, without any SMTP handshake, and no credentials are required or stored. Use `tcp` mode when you only need to confirm the port is reachable.