The Transport Independent RPC library (TI-RPC) is a replacement for the
standard SunRPC library in glibc which does not support IPv6 addresses.
This implementation allows the support of other transports than UDP and
TCP over IPv4

A mail server using the POP3 protocol. The daemon also supports the
more secure APOP protocol.

You must agree to the license in
/usr/share/doc/packages/qpopper/License.txt before you can use qpopper.

After installation, activate the server in the /etc/inetd.conf or
/etc/xinetd.d/qpopper file.

Rpcbind is a replacement for portmap. Whereas portmap supports only UDP
and TCP transports over INET (IPv4), rpcbind can be configured to work
on various transports supported by the TI-RPC. This includes TCP and
UDP over IPv6. Moreover, rpcbind provides additional functions in
regards to portmap.