use regex function like below
string[] aryMailId = txtcc.text.split(",");
for (i=0;i<arraylist.length;i++)>
{
string Inputstr=aryMailId[i];
Match rex = Regex.Match(Strings.Trim(InputStr),"^([0-9a-zA-Z]([-.\\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\\w]*[0-9a-zA-Z]\\.)+[a-zA-Z]{2,3})$", RegexOptions.IgnoreCase);
if (rex.Success == false)
{
}
}
Happy Coding!
:)