True or False: When configuring Delivery Route Definitions, only the IP address can be entered and not the hostname of the mail server.

The statement is false because when configuring Delivery Route Definitions in Mimecast, you have the flexibility to enter either an IP address or a hostname of the mail server. This capability allows for more versatility in how you manage delivery routes, accommodating various network configurations and preferences. Utilizing hostnames can be particularly beneficial for environments where IP addresses might change, allowing for more dynamic and robust routing options. Therefore, saying that only the IP address can be used is inaccurate, as both options are valid for defining delivery routes in Mimecast.