You must use an API key to authenticate through the SendGrid provider.

Obtaining an API Key

To obtain an API key, follow the steps below:

1. Log into SendGrid.
2. Click Settings.
3. Click API keys.
4. Click Create API Key.
5. Choose the Permissions the API Key should have, either Full Access or Restricted Access. The API key is then displayed.

NOTE: If you want access to Email events, you must purchase the Email Activity History add-in of SendGrid. If using a Restricted Access key, you must give it the messages.read and email_activity.read scopes.