You could use a Regular Expression to do this.

At 15:22 15/02/03 +0330, you wrote:
>Hello,
>
>Sorry, I've asked to many questions today.
>and maybe boring questions. :(
>I'll ask it short:
>
>do you know any predefined function to clean up a messy String?
>for example:
>- change Enter to \n. (most important one for me)
>- &  -->&
>- > to &gt
>- .......
>
>thanks
>
>
>