---
title: "SMTP Sampler"
description: "Configure the JMeter SMTP Sampler samplers: properties, defaults, and practical usage notes for building reliable load tests."
url: https://docs.jmeter.ai/components/smtp-sampler/
lastUpdated: 2026-10-01
source: docs.jmeter.ai
---

# SMTP Sampler

*Part of the **Samplers** category. Also documented in context in the [full Component Reference](/user-manual/component-reference/#smtp-sampler).*

![SMTP Sampler](/images/screenshots/smtp_sampler.png)

The SMTP Sampler can send mail messages using SMTP/SMTPS protocol.
It is possible to set security protocols for the connection (SSL and TLS), as well as user authentication.
If a security protocol is used a verification on the server certificate will occur.

Two alternatives to handle this verification are available:

**`Trust all certificates`**
: This will ignore certificate chain verification

**`Use a local truststore`**
: With this option the certificate chain will be validated against the local truststore file.

| Name | Required | Description |
| --- | --- | --- |
| Server | Yes | Hostname or IP address of the server. See below for use with `file` protocol. |
| Port | No | Port to be used to connect to the server. Defaults are: SMTP=25, SSL=465, StartTLS=587 |
| Connection timeout | No | Connection timeout value in milliseconds (socket level). Default is infinite timeout. |
| Read timeout | No | Read timeout value in milliseconds (socket level). Default is infinite timeout. |
| Address From | Yes | The from address that will appear in the e-mail |
| Address To | Yes, unless CC or BCC is specified | The destination e-mail address (multiple values separated by “`;`”) |
| Address To CC | No | Carbon copy destinations e-mail address (multiple values separated by “`;`”) |
| Address To BCC | No | Blind carbon copy destinations e-mail address (multiple values separated by “`;`”) |
| Address Reply-To | No | Alternate Reply-To address (multiple values separated by “`;`”) |
| Use Auth | No | Indicates if the SMTP server requires user authentication |
| Username | No | User login name |
| Password | No | User login password (N.B. this is stored unencrypted in the test plan) |
| Use no security features | No | Indicates that the connection to the SMTP server does not use any security protocol. |
| Use SSL | No | Indicates that the connection to the SMTP server must use the SSL protocol. |
| Use StartTLS | No | Indicates that the connection to the SMTP server should attempt to start the TLS protocol. |
| Enforce StartTLS | No | If the server does not start the TLS protocol the connection will be terminated. |
| Trust All Certificates | No | When selected it will accept all certificates independent of the CA. |
| Use local truststore | No | When selected it will only accept certificates that are locally trusted. |
| Local truststore | No | Path to file containing the trusted certificates. Relative paths are resolved against the current directory. Failing that, against the directory containing the test script (JMX file). |
| Override System SSL/TLS Protocols | No | Specify a custom SSL/TLS protocol as space separated list to use on handshake example `TLSv1 TLSv1.1 TLSv1.2`. Defaults to all supported protocols. |
| Subject | No | The e-mail message subject. |
| Suppress Subject Header | No | If selected, the “`Subject:`” header is omitted from the mail that is sent. This is different from sending an empty “`Subject:`” header, though some e-mail clients may display it identically. |
| Include timestamp in subject | No | Includes the `System.currentTimemillis()` in the subject line. |
| Add Header | No | Additional headers can be defined using this button. |
| Message | No | The message body. |
| Send plain body (i.e. not multipart/mixed) | No | If selected, then send the body as a plain message, i.e. not `multipart/mixed`, if possible. If the message body is empty and there is a single file, then send the file contents as the message body. :::note Note: If the message body is not empty, and there is at least one attached file, then the body is sent as `multipart/mixed`. ::: |
| Attach files | No | Files to be attached to the message. |
| Send .eml | No | If set, the `.eml` file will be sent instead of the entries in the `Subject`, `Message`, and `Attach file(s)` fields |
| Calculate message size | No | Calculates the message size and stores it in the sample result. |
| Enable debug logging | No | If set, then the “`mail.debug`” property is set to “`true`” |

## Related

- [API Load Testing Guide](/topics/api-load-testing/)
- [cURL & HAR to JMX Converter](/tools/curl-to-jmx/)
- [Full Component Reference](/user-manual/component-reference/)
- [Functions and Variables](/user-manual/functions/)