Split Email string into 3 TextBox ASP.Net

when I select a row from a grid view to update the fields of this row appear in many textboxes and I have an email field which I want it to split into 3 textboxes to update ex: if I have this email: xx@yy.com I want the xx appears in first textbox and yy appears in second textbox and com appears in third textbox I actually did it correctly but it raises an error when trying split the last part (com) here is my code:

txt1_email1_update.Text="";
            txt1_email1_update.Text=txt_email_update.Text.Split('@')[0];
            txt2_email1_update.Text = "";
            txt2_email1_update.Text = txt_email_update.Text.Split('@')[1];
            txt3_email1_update.Text = "";
            txt3_email1_update.Text = txt_email_update.Text.Split('.')[2];