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E-Mail (SMTP Client)

The SMTP Client feature lets your device send email through an outgoing mail server. Use it for alarms, daily reports, or any notification that should reach a person directly.

The feature holds the server connection details. Messages are sent with the Send Email block, which only sets the recipient, subject and body.

Availability

The SMTP Client is available on Zephyr-based devices with a network interface (Ethernet, Wi-Fi or Cellular).

Configuration​

General​

  • SMTP Client Enabled: turns the client on. All other properties are disabled while it is off.
  • SMTP Server: hostname or IP address of the outgoing mail server, for example smtp.gmail.com.
  • Port: TCP port of the server. Defaults to 465.
  • Connection Security: how the connection is protected.
    • None: plain, unencrypted connection (typically port 25).
    • STARTTLS: starts plain and upgrades to TLS (typically port 587).
    • SSL/TLS: TLS from the first byte (typically port 465). This is the default.
  • From Address: the address messages are sent from. It is used as both the envelope sender and the From: header.

Authentication​

  • Authentication Method: None, PLAIN, or LOGIN (default). Choose None for servers that do not require a login.
  • Username: account name used to log in, often the full email address.
  • Password: account password. Many providers require an app-specific password instead of your normal password.

The username and password are disabled when the method is None.

Advanced​

  • Timeout (ms): how long to wait for the server to answer a command before the send fails. Defaults to 10000.
  • Log Level: verbosity of the client's log output, from None to Debug.

Linking to Settings​

SMTP Server, Port, From Address, Username and Password can be linked to settings. This lets each installed device use its own mail account, configured from the Web Console, without rebuilding the firmware.

Dependencies​

The feature automatically adds the socket and DNS libraries to the project. When Connection Security is anything other than None, the MbedTLS library is added as well.

Common Providers​

ProviderServerPortSecurity
Gmailsmtp.gmail.com465SSL/TLS
Outlook / Microsoft 365smtp.office365.com587STARTTLS

Check your provider's documentation for current values. Most providers also require an app password or an explicit setting to allow SMTP access.

See Also​