To use SendGrid or any other SMTP server with Ory Kratos, you need to configure the SMTP settings in your Kratos configuration file. The error you're seeing indicates that the

connection_uri

property is missing in your configuration. This property is required to establish a connection with your SMTP server. Here's an example of how you can set it up:

yaml courier:    smtp:    connection_uri: <smtp://username:password@server:port/>

Replace

username:password@server:port/

with your SendGrid SMTP credentials. If your SMTP server enforces certificate-based authentication, you can configure the client certificate and client private key to use to connect to the server. The files must contain PEM encoded data:

yaml courier:    smtp:    client_cert_path: /somepath/client.cert    client_key_path: /somepath/client.key

You can also configure custom SMTP headers, HELO/EHLO identifier, and other settings as per your requirements. Please refer to the [Ory Kratos documentation](https://www.ory.sh/docs/kratos/self-hosted/mail-courier-selfhosted) for more details on configuring the mail courier in self-hosted Ory Kratos.