可以使用以下步骤来实现：

1. 创建一个Logic App，并添加一个“Recurrence”触发器来指定Logic App的执行间隔。

2. 接下来，添加一个条件测试器，以便只有当指定条件为True时才会继续执行Logic App。

3. 如果条件为True，则执行“Get attachments”操作，以获取要附加到电子邮件中的文件。

4. 如果未找到任何文件，则结束Logic App。

5. 如果找到文件，则执行“Send an email”操作，并将文件添加到附件字段中。

下面是示例代码：

{
    "$connections": {
        "value": {
            "email_1": {
                "connectionId": "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Web/connections/email-1",
                "connectionName": "email-1",
                "id": "/subscriptions/{subscriptionId}/providers/Microsoft.Web/locations/{location}/managedApis/email"
            }
        }
    },
    "triggers": {
        "Recurrence": {
            "type": "Recurrence",
            "recurrence": {
                "frequency": "Hour",
                "interval": 1
            }
        }
    },
    "conditions": {
        "only_when_file_exists": {
            "type": "If",
            "inputs": {
                "left": "@equals(length(body('Get_attachments')?['$content']),0)",
                "right": false
            }
        }
    },
    "actions": {
        "Get_attachments": {
            "type": "Get_attachments",
            "inputs": {
                "body": {
                    "MailId": "Insert Mail Id here",
                    "MailFolder": "Insert Mail Folder here"
                },
                "host": {
                    "connection": {
                        "name": "@parameters('$connections')['email_1']['connectionId']"
                    }
                }
            }
        },
        "Send_email": {
            "type": "Send_email",
            "inputs": {
                "body": {
                    "To": "Insert To email here",
                    "Subject": "