when parse mail body, how to remove quoted message

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For example

this is the mail message line one
>this is the mail message line two
>this is the mail message line three

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how to remove line two and line three?
shoud i have to using special tag in mail.
so when someone reply the mail. quoted message will
be wrapped in special tag. much like move javascript?

or any more easy clever way to move line two or three.

Thanks in advance