On the return by the post office of a letter containing a notice, the Authority may require some other notice to be given or may authorise substituted service of the notice, or it may proceed without further notice, if, in the circumstances, it thinks fit to do so.
S.I. No. 483/2012
Land Registration Rules 2012
7 December 2012
www.irishstatutebook.ie/eli/2012/si/483