您可以使用groovy的File.exists方法来检查给定的文件是否存在，并相应地运行脚本。

def file = new File( 'path/to/index.html' )

// If it exists
if( file.exists() ) {
  emailext(to: 'jane.doe@foo.com',
        subject: 'Build report',
        mimeType: 'text/html',
        body: '${FILE,path="path/to/index.html"}',
  )
}

post {
    always {
        echo 'I will always say Hello again!'
        
        emailext body: '${FILE,path="report/report.html"}',
            mimeType: 'text/html',
            to: "example@example.com",
            subject: "Daily Automation Report"
    }
}