I really donīt know if what I will sugest already exists.
After some time, everybody has a big email box. The problem in my opinion is when people have many attached files.
For example, a person having an email account with more than 50GB. In general, when this person do a search he wants a quick search and want to see the text content of the search results. But, he has to wait the loading for all attached files for each email he try to see. This is a real problem, because this spends too much time.
I donīt know if is too dificulty to implement a Email System having an email server independent of a file server. When the email is received the email server automatically creates a link to the file, with a special identification code and encryption, for example, and send the file to the file server. Optionally, by means a md5 algorithm or similar, will be possible to identify repeated files and point the link to the same file, avoiding file redundancy.
When the person select an email, he will see only the text content. If he click on the attached file the server opens the file through the file server.
In the webmail of this Email System would be possible to delete the all attached files or that files you selected for each email. The file server will delete a file only after there is no link pointed to that file. So, if a person delete the file and another person has the same file on his box, only the link will be deleted, in this case the link can be restored. But, if the last person delete this file, the link and the file will be deleted and nobody could restore the file.
In a backup you choose preserve only the text content, only the file content (but needing some security features that only by means of the person account this can be accessed), or both content. Optionally, an action log can be created on the email having the history of performed actions.
This is a way to preserve the text content and delete that files that there is no importance to the person, and a way to have an express mail system having to load only text.
I hope I was clear.