Retrieving deleted messages from iCloud in an email thread

I have a specific email thread and how can I and how can Igoing on a chat. This thread is about six months old and the original has been backed up since then the person I was communicating with deleted on the active thread portions of the message that was sent. Are those portions still in iCloud? If so, how can I retrieve them or view them? Thank you.

[Re-Titled by Moderator]