Mine tend towards the latter for both internal and external and only get a little more expository if it’s a closedown period and I’m adding leave to one end of it, but that’s a simple “The organisation is shut between X and Y. For emergencies during this time please contact Team. I am on leave between Z and B and will not be accessing my email during this time. Please contact Email Address if your enquiry is urgent otherwise I will attend to your email as soon as is practicable upon my return.”
If instead you ask your co-workers to cc or bcc on replies then you will know which have been dealt with. (I think for internal mails it’s more reasonable to ask that if the original person contacts someone else, they cc you so you know who is dealing – and in smaller organisations where people know you personally you could also send a mail round the day before you leave to say you’re going to be out and to ask that any enquiries are directed to [name]in your absence, to try to avoid them coming into your inbox in the first place.

7.) Добро пожаловать в адвокатскую контору «Вася Пупкин и Ко». К сожалению, мы в настоящее время не можем ответить на ваш звонок лично, так как вы пытаетесь с нами связаться во время нашего ежегодного отпуска. Вы можете отправить нам письмо по электронной почте [email protected] – мы свяжемся с вами как можно скорее после отпуска. В неотложных случаях, пожалуйста, свяжитесь с нашим представителем в офисе. Информацию можно найти на нашем сайте www.lawoffice-johndoe.de. Большое спасибо за ваш звонок – до свидания.
Sorry I missed you. I’ll be out of the office and slow to respond until after the break. While I have you, though, help settle an argument among my colleagues and me: Die Hard 1: The Office Christmas Party Gone Wrong. Die Hard 2: Airport Conspiracy. Die Hard 3: Samuel L. Jackson. Enough said. Die Hard 4: Cyberthreat. Die Hard 5: You should probably not pick this one. Impossible! It’s like choosing a favorite child!