Pro and Cons : Assign /32 subnet on FortiMail interface

Hi, Does anyone know what the pro and cons if I use /32 subnet on FortiMail physical interface? For example, there is a subnet of 10.10.10.0/29 and I assign port1 with IP 10.10.10.2/32. In the routing table, I set the default route with Gateway 10.10.10.1 and interface port1.