<tab id="MyTab" label="AmdocsTool" getVisible="MyTab_GetVisible">
        <group id="ContentGroup" label="Content">
          <button id="textButton" label="Apply for leave"
               screentip="Text" onAction="OnTextButton"
               supertip="Inserts text at the cursor location."/>
          <button id="tableButton" label="Cancel Leave"
               screentip="Table" onAction="OnTableButton"
               supertip="Inserts a table at the cursor location."/>
        </group>
      </tab>

      <tab idMso="TabMail">
        <group id="ContentGroup1" label="Content">
          <button id="textButton1" label="Apply for leave"
               screentip="Text" onAction="OnTextButton1"
               supertip="Inserts text at the cursor location."/>
          <button id="tableButton1" label="Cancel Leave"
               screentip="Table" onAction="OnTableButton1"
               supertip="Inserts a table at the cursor location."/>
        </group>
        
      </tab>




public bool MyTab_GetVisible(Office.IRibbonControl control)
        {
            if (control.Context is Outlook.Explorer)
            {
                Outlook.Explorer explorer =
                    control.Context as Outlook.Explorer;
                Outlook.Selection selection = explorer.Selection;
                if (selection.Count == 1)
                {
                    if (selection[1] is Outlook.MailItem)
                    {
                        Outlook.MailItem oMail =
                            selection[1] as Outlook.MailItem;
                        if (oMail.Sent == true)
                        {
                            return true;
                        }
                        else
                        {
                            return false;
                        }
                    }
                    else
                    {
                        return false;
                    }
                }
                else
                {
                    return false;
                }
            }
            else if (control.Context is Outlook.Inspector)
            {
                Outlook.Inspector oInsp =
                    control.Context as Outlook.Inspector;
                if (oInsp.CurrentItem is Outlook.MailItem)
                {
                    Outlook.MailItem oMail =
                        oInsp.CurrentItem as Outlook.MailItem;
                    if (oMail.Sent == true)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                else
                {
                    return false;
                }
            }
            else
            {
                return true;
            }
        }