Many applications, such as Nextcloud and Mattermost, require SMTP server configuration to send notification messages to users and service administrators.
You can configure the same SMTP server for all installed applications by
accessing the Email notifications card inside the Settings page.
To enable the feature, click on Send notifications with an SMTP
server and fill the required details.
If a Mail application instance is already installed in the cluster, choose
the Use Mail app instance option. Then refer to the section
:ref:`relay-rules-section` for further information about the configuration
of Mail.
Instead, choose Manual configuration to specify SMTP server parameters
in this form. Available fields are:
- SMTP server: The host name or IP address of the SMTP server
- SMTP port number: TCP port number of the server. Common values are 587, 25, 465, 2525.
- SMTP encryption: Encryption used by the server. TLS is a widely used encryption protocol that encrypts a connection from the moment it is established. STARTTLS is the standard encryption method for SMTP. If both the client and server support it, the connection is encrypted after both sides agree to use it.
- Verify the TLS certificate: If encryption is used, this switch controls if the certificate used to encrypt the connection must be signed by a trusted authority or not. If the server presents a self-signed certificate, turn off this switch to accept it.
- Username and Password: If the server requires SMTP authentication, fill the credential fields; otherwise leave them blank.
After saving the settings, a SMTP connection to validate the form parameters is immediately started. In some cases, validation is successful, but messages may still fail to be delivered. It is recommended to check that individual applications can successfully send messages with the new settings.