This is problematic because RFC1918 IP addresses are not routable over the internet so any FTP client using the unroutable IP address returned by the FTP server will be unable to send further data packets to the server.

Jan 23, 2019 In IP networking, a private network is a network that uses private IP address space. Both the IPv4 and the IPv6 specifications define private IP address ranges. These addresses are commonly used for local area networks (LANs) in residential, office, and enterprise environments. Discover how IP addresses are constructed and how to understand them better by relating them to a picture rather than converting binary numbers or memorizing charts. Learn the benefits that subnetting in your head provides in every aspect of IT networking, including routing protocols, access control lists, and network address translation. Non-Routable (Private) IP RFC 1597 provides for a group of Internet Networks that will never be assigned. Furthermore, these addresses will not r oute through the Internet. This makes them the proper choice for use in your home or company Intranet We recommend non-routable IP for most networks. These IP addresses have IP addresses: – Note that only a portion of the “172” and the “192” address ranges are designated for private use. The remaining addresses are considered “public,” and thus are routable on the global Internet. host ip-address Through checking the spam blacklist and confirming with the remote email server, the rejections or blacklisting from the recipient email server can be confirmed. In order to secure the server in case of the blacklisting, scan the server and remove all spamming scripts and implement security measures.

As I understand it, there are several "non-routable" IP ranges: class A reserved space class B reserved space class C reserved space class E reserved for

Link-local address - Wikipedia

routing - When to use routable vs non-routable IP

Configuring FileZilla FTP to use active mode to resolve Oct 07, 2011 FTPS Connection Issue / Unroutable Address : The Official May 17, 2019 What is the difference between routable and non- routable Routable protocols can be used to send data between networks and these protocols contains device address(i.e.:MAC Adress) and network addresses (i.e.:IP Address). and it can be routed any where. these protocols are used in layer3 devices (Routers). example:TCP/IP, Apple talk, SNA Non-Routable protocols can be used send data inside the network.