Encryption serious problem

Hello all, this is my first topic. Thank you in advance for your answers.

For my PDF I use 'Encryption' to allow the user to ONLY print the document. When I open this pdf with a reader (Acrobat Reader, Foxit) the behaviour is correct and all actions are blocked (except printing)

The problem occurs when I open it with a browser directly from an email.
For example if you open an attached pdf in web outlook with firefox, you can COPY content from the document without problem!
Same thing opening the attached pdf in gmail web.

How is it possible? Browsers or webmail can bypass encryption so easily?
I use pdf creator free v4.10 build 13336 so the encryption is max 128 bit aes.

Is this the problem?