If those options are greyed out, there's a Group Policy in place preventing you from changing those options.
It's most likely set like this because its totally pointless to set those permissions on an email to be restrictive and leaving them enabled just leads to users accidentally clicking things which generates superfluous service tickets (Why cant I forward this email?!?!?! etc.)
Even with all of those options enabled, there's absolutely nothing stopping someone from simply opening a new email and writing the same thing word for word. On the flip side, any time someone *needs* to forward an email, they cant. Blocking forwarding/copying/pasting in outlook does nothing but kneecap workflows.
I'm gonna go out on a limb and say IT gave you the simple "can't do it" because A) users could still retype the email by hand and B) explaining the rationale of every configured group policy in technical detail to any random user who asks is a huge waste of everyone's time