>>the principle
years ago CompuServe had a strict "author's rights maintained" policy; after AOL bought CompuServe that policy changed to "AOL, and anyone else they said, had full rights to anything and everything you post"
many, many authors, photographers, experts in every field and endeavor deleted their posts/files/content - it was the beginning of the end . . .
I had posted many articles/files/information on specific topics - along with software programs, etc., and I deleted every last one.
I'd put a lot of time & effort into that work and I was not about to permit AOL to assume ownership.
(1) if it's a secret, don't write it in email.
(2) if you cannot undergo the risk someone will steal/copy your work, do not post it on the internet.
and that is an entirely different situation from any site's "policy" - locks only keep honest people honest. the crooks just break the lock and steal your stuff anyway.
here's photobucket - they say they do not claim rights, but anyone who can "see" the material is free to use it in any fashion and in any media that viewer chooses - and note they do not even preclude commerical use of your material.
Proprietary Rights in Content on Photobucket.
6.1 Photobucket does not claim any ownership rights in the text, files, images, photos, video, sounds, musical works, works of authorship, applications, or any other materials (collectively, "Content") that you post on or through the Photobucket Services. By displaying or publishing ("posting") any Content on or through the Photobucket Services, you hereby grant to Photobucket and other users a non-exclusive, fully paid and royalty-free, worldwide, limited license to use, modify, delete from, add to, publicly perform, publicly display, reproduce and translate such Content, including without limitation distributing part or all of the Site in any media formats through any media channels, except Content marked "private" will not be distributed outside the Photobucket Services. Photobucket and/or other Users may copy, print or display publicly available Content outside of the Photobucket Services, including without limitation, via the Site or third party websites or applications (for example, services allowing Users to order prints of Content or t-shirts and similar items containing Content). After you remove your Content from the Photobucket Website we will cease distribution as soon as practicable, and at such time when distribution ceases, the license to such Content will terminate. If after we have distributed your Content outside the Photobucket Website you change the Content’s privacy setting to "private," we will cease any further distribution of such "private" Content outside the Photobucket Website as soon as practicable.