The network configuration files store extended per room configurations for communicating outside world into a room.
The usual way is to use the Webcit or the Citadel commandline client to edit these configs. Supported configuration types are:
POP3 is here to synchronize mailboxes. You can use it to collect your mails from other sites.
RSS is a way to stay informed whats happening on your news sites, Blogs, tweets, and so on. Citserver does HTTP-Polling for these.
Citadel can distribute the postings of a room to email recipients either in per Post mode, or all posts as a daily digest; Depending on the settings of an aide, users can start/stop their abbonement via the webcit List-Subscription Web Selfcare interface.
Citadel has its own TCP communication protocol for fedarated citadel networks; here you can configure which room from a remote site maps to this room. Once messages appear on one site, they make it over; similar to email, this is no realtime protocol.