In case of security threats or other anomalous activities detected on SQL servers, it is crucial to let the concerned people know. Providing the email address to receive alerts ensures that any detection of abnormal activities is reported as soon as possible, so for any potential risk, early mitigation could be enabled.
We recommend you to ensure that 'Email service and co-administrators' is 'Enabled' for MySQL servers.
resource "azurerm_mssql_security_alert_policy" "recommended" {
...
email_account_admins = true
}