espocrm-base/application/Espo/Modules/Crm/Resources/metadata/clientDefs/MassEmail.json

{
  "controller": "controllers/record",
  "recordViews": {
    "detail": "crm:views/mass-email/record/detail"
  },
  "views": {
    "detail": "crm:views/mass-email/detail"
  },
  "formDependency": {
    "status": {
      "map": {
        "Complete": [
          {
            "action": "setReadOnly",
            "fields": [
              "status"
            ]
          }
        ],
        "In Process": [
          {
            "action": "setReadOnly",
            "fields": [
              "status"
            ]
          }
        ],
        "Failed": [
          {
            "action": "setReadOnly",
            "fields": [
              "status"
            ]
          }
        ]
      },
      "default": [
        {
          "action": "setNotReadOnly",
          "fields": [
            "status"
          ]
        }
      ]
    }
  }
}