The DCC SEND command has two things that make it out of date:
1) Is that it still uses IPv4 encoding for the IP address. There is very little documentation on it, it is out of date, and causes problems with other IRC clients. It should at the very least
2) The command itself is out-of-date. Instead, XMIT should be used. To maintain backwards compatibility, SEND can still be enabled but right now XMIT doesn't even seem to be supported.