To check if a specific port is open on a server, you need to run a telnet command in your system console as not all hosting services might support it. This is useful if you want to check the port’s availability before integrating it with your email service or if you are trying to configure SMTP on your website or app and get an error message stating that the connection was refused.
Access your system console
To run a telnet command, you first need to access your system console:
- Press Windows+R keys together.
- On the Run window, enter cmd and click OK (or press Ctrl+Shift+Enter to run it as administrator).
- The Windows command prompt window appears.
- Press Ctrl+Alt+T keys together.
- The Linux terminal window appears.
- Press the F4 key.
- Enter terminal in the Spotlight's search field and press Enter.
- The macOS terminal window appears.
Use a Telnet command to check the connection
To check the connection with the SMTP port, use the following telnet command:
- Write down telnet smtp-relay.brevo.com ### in your console and make sure to replace ### with the port number you're trying to connect to, which is either 587, 2525, or 465.
- If the SMTP port is not blocked, a blank screen or the 220 response appears.
- If the Unable to connect or Connection refused message appears, it means that the port is blocked. In this case, we recommend you try using one of our other SMTP ports or contact our support team with a screenshot of the message you got.