Hai just try it
in asp.net or ext:
<ext:textarea runat="server" id="text1" text="someone@gmail.com" xmlns:ext="#unknown" />
<ext:textarea runat="server" id="text2" text="someone@yahoo.com" xmlns:ext="#unknown" />
in code behind(.cs page):
MyMail.CC = lsEmailCC;
lsEmailCC = text1.Text + text2.Text;