I use NextCloud via my private cloud on the web. Unfortunately, many of my received emails are without content. The sender and subject line are there, but neither the message nor the attachments are found. OPS = Ubuntu 22.04.3 LTS. Client = Firefox 117.0.1. My cloud provider “Hosting.de” refers to NextCloud. Does anyone know this effect?
Try asking your hosting provider for assistance directly. They will have the logs and info to help you.