Hi, I am currently attending a training session. As a result, my reply might take a bit longer than usual. I apologize for that. I will be able to respond in a more timely manner starting from [DATE].
Yeah, announcing you were going to delete emails unread and expecting the sender to resend when you return would NEVER fly in my office. I’d get executive complaints about that, especially if it went to a client or outside party – if a client can’t reach you, they will reach out to someone else who may not work at your organization and you lose business. I feel like this delete-it-all philosophy would only work for an entirely internal role where timelines are more relaxed, and even then, I feel it’s a bit unprofessional to foist your own catch-up work onto others, especially if they’ve been backfilling for you while you were OOO.

It’s your last day before the vacation starts, you are rushing through your to-do list and suddenly you realize- I need to write an OOO email!
4.) Bienvenue chez John Doe Solutions. En raison d'un événement en interne, notre secrétaire n’est pas disponible aujourd'hui. Vous êtes le bienvenu à laisser un message. Nous serons de nouveau à votre service lundi. Merci pour votre compréhension.