SMTP Test Tool

Test an SMTP server by sending a real test email, with TLS/SSL and username and password login.

SMTP Server

Host name or IP address of your SMTP server.

Port

The default port is 25; mail clients usually use 587 or 465.

Email From

Email To

The test email is sent to this address.

Username

Use Secure Connection

Password

Security Type Use Authentication

A short test email is sent through your server. Your password is used only for this test and is never stored.

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Clear instructions

Find steps, examples and limitations below.

Use online

Open the tool in a supported web browser.

Free to use

No sign-up required. Tool-specific limits may apply.

How to use the SMTP Test Tool

The SMTP test tool checks that your mail server can really send email. It connects to the server by host name or IP address, secures the connection with TLS or SSL if you choose, logs in with your username and password, and sends a short test message from your Email From address to your Email To address. You see whether the email was sent and, if not, the exact step and server reply that stopped it.

1 Enter your SMTP server host name or IP address and its port (click 25, 2525, 465 or 587 to fill one in), then the Email From address and the Email To address that should receive the test email.
2 Tick Use Secure Connection if the server needs encryption and choose TLS (STARTTLS, usually port 587) or SSL (usually port 465). Keep Use Authentication ticked and enter the username and password if the server needs a login.
3 Click Test SMTP. When the test succeeds, check the Email To inbox (and spam folder) for the message.

Example and practical tips

To test a Gmail account, enter smtp.gmail.com, click 587 so TLS is selected, and use your address with an app password. A "535 Authentication failed" reply in the conversation means the username or password was rejected; "Could not connect" usually means the port is blocked or wrong.

Frequently asked questions

What is SMTP?

SMTP (Simple Mail Transfer Protocol) is the protocol email clients and servers use to send mail. It runs over TCP and is also used to pass messages from one mail server to another.

Is SMTP port 25 or 587?

Both. Port 25 is used between mail servers, and is often blocked for home and cloud networks. Port 587 with STARTTLS is the standard for email clients sending mail, and port 465 uses SSL from the start.

What is the difference between TLS and SSL here?

TLS (STARTTLS) connects without encryption and then upgrades the connection, usually on port 587. SSL encrypts the connection from the first byte, usually on port 465. Both use modern TLS encryption; the names describe how the connection starts.

Is my password stored?

No. Your username and password are sent to your SMTP server only to log in for this one test, are masked in the conversation log, and are never saved or logged.

Why did the test fail?

The error shows the step and the reply from your server. Common causes are a blocked or wrong port, the wrong security type, a rejected username or password (some providers need an app password), or a server that does not allow the Email From address.