Prompt injection is really a problem only for some usecases. A hard use case is for example to summarize a list of all new emails into a single summay. In this

Prompt injection is really a problem only for some usecases. A hard use case is for example to summarize a list of all new emails into a single summay. In this case ensuring that a single incoming email doesn't contain instructions to change the summary into whatever text is quite hard. On the other hand summarizing emails one by one and displaying a list of summarized emails wouldn't be an issue as you could ensure that the LLM only has access to a single email at a time and if one email contained instructions to change the summary, the sender might as well have sent that instead.