If you leave me a comment through email, the comment and its metadata are retained indefinitely. This is so I can answer follow-up comments automatically instead of holding them in a moderation queue.
In conclusion, for users that register on my website, I will only store the personal information they provide in a user profile. In addition, the website administrators can only see and edit that information. After that, the information is used exclusively for Birthday greetings and special announcements ONLY!