You can send email by using SendGrid bindings in Azure Functions. Azure Functions supports an output binding for SendGrid.
Note: When you're using the Consumption plan, instances of the Azure Functions host are dynamically added and removed based on the number of incoming events.
Reference:
https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-sendgrid
https://docs.microsoft.com/en-us/azure/azure-functions/functions-scale#consumption-plan