{
 Here is some code I successfully used te determine
 the DEFAULT mailaccount, which is used in
 Outlook Express, to send outgoing mail via SMTP.
}
procedure TForm1.ReadRegistryDefaults;
var
 Registry: TRegistry;
 AccountStr: string;
begin
 Registry := TRegistry.Create;
 try
  Registry.RootKey := hkey_CURRENT_USER;
  if Registry.OpenKey('software\microsoft\internet account manager', False) then {}
  begin
  AccountStr := Registry.ReadString('default mail account');
  Registry.CloseKey;
  if (AccountStr <> '') then
  if Registry.OpenKey('software\microsoft\internet account manager\accounts\' +
  AccountStr, False) then {}
  begin
  Edit_Server.Text := Registry.ReadString('SMTP Server');
  Edit_Account.Text := Registry.ReadString('SMTP Email Address');
  Registry.CloseKey;
  end;
  end;
 finally
  Registry.Free;
 end;
end;