FirewallHost Parameter (Add-IMAP Cmdlet)
Name or IP address of firewall.
Add-IMAP -FirewallHost string
If a FirewallHost is given, requested connections will be authenticated through the specified firewall when connecting.
If the FirewallHost parameter is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, the FirewallHost parameter is set to the corresponding address. If the search is not successful, an error is returned.