Letterbox Cutout

[tmf786]

Anyone have any idea on whether it would be safe to cut out a section of the front wall in an archway to insert one of these letterbox options?

Veritcal: http://www.lettasafe.co.uk/16/LS17/highway-through-wall-letter-chute/product.php

Horizontal: http://www.lettasafe.co.uk/16/LS16/oakley-through-wall-letter-chute/product.php

Many thanks

 

[tmf786]

Just for anyone's reference - this is not doable as the arch transfers its weight onto the section therefore the recommendation is not to cut it.